Answers
Answer:
E, needs more info to be determined
Step-by-step explanation:
We know that Kai takes 30 minutes round-trip to get to his school.
One way is uphill and the other is downhill.
He travels twice as fast downhill than uphill.
This means that uphill accounts for 20 minutes of the round-trip and downhill accounts for 10 minutes of his trip.
However, even with this information, we do not know how far his school is.
In order to figure out how far away his school is, we would need more information about the speed at which Kai is traveling.
Simply knowing that he travels twice as fast downhill is not enough.
This question could only be solved by knowing how many miles Kai travels uphill or downhill in a given time.
Related Questions
i
dont
get
this
help
rn
Answers
Answer:
6 first box. 12 second box. 21 third box. 10 fourth box. 4 fifth box.
Step-by-step explanation:
Look for common denominaters, that will show you what to multiply the equation by to get rid of fractions.
Find dw/ds using the appropriate Chain Rule for w=y^3-4x^2y where x=e^s and y=e^t, and evaluate the partial derivative at s=-3 and t=5 . Round your answer to two decimal places.
Answers
Answer:
-2.95
Step-by-step explanation:
Given the functions w=y^3-4x^2y where x=e^s and y=e^t, to get dw/ds, we will use the chain rule for composite functions as shown;
dw/ds = dw/dx*dx/ds + dw/dy*dy/ds
dw/dx = -8xy
dx/ds = e^s
dw/dy = 3y²-4x²
dy/ds = 0 (since there are no s variable in the function)
Substituting the differentials into the formula above;
dw/ds = -8xy(e^s) + 3y²-4x²(0)
dw/ds = -8xy(e^s)
Substituting s = -3 and t = 5 into the resulting function;
dw/ds = -8(e^s)(e^t)(e^s)
dw/ds = -8(e^2s)(e^t)
dw/ds = -8(e^-6)(e^5)
dw/ds = -8*0.00248*148.413
dw/ds = -2.945 ≈ --2.95 (to 2 dp)
Find y................
Answers
Answer:
[tex] y = 3 [/tex]
Step-by-step explanation:
Given the above right angled triangle, we would use a trigonometric ratio formula to find y.
Given angle = 30°
Hypotenuse = 6
Opposite side = y
Solve for y using the trigonometric ratio formula as follows:
[tex] sin(X) = \frac{opposite}{hypotenuse} [/tex]
[tex] sin(30) = \frac{y}{6} [/tex]
Multiply both sides by 6
[tex] sin(30)*6 = \frac{y}{6}*6 [/tex]
[tex] 0.5*6 = y [/tex]
[tex] 3 = y [/tex]
[tex] y = 3 [/tex]
A recent study found that toddlers who have a diet high in processed foods may have a slightly lower IQ later in life. The conclusion came from a long-term investigation of 14,000 people whose health was monitored at 3,4,7, and 8 years of age.
a) One analysis found that of the 4000 children for which there were complete data, there was a significant difference in IQ between those who had had "processed" (i.e., junk) food and those who followed health-conscious diets in early childhood. Is this an experiment? Why or why not?
b) Discuss at least two explanatory factors that could conceivably confound the relationship between diet and IQ.
Answers
Answer:
A) it is not an experiment it is an observational study/analysis
B) i)Foods high in fats and sugar affects IQ (ii)Foods that contain the required classes of food affects IQ positively
Step-by-step explanation:
A) An analysis carried out on 400 children using the data derived from the long term investigation can not be said to be an experiment but an observational analysis this is because the complete data has been provided already from the long term investigation already. hence it can only be observed
B ) i) foods high in fats and sugar affects The IQ of children later in life as seen from the results of the observational study that children whom had processed foods had a significant negative difference in IQ when compared with children who had health-conscious diets
ii) following health conscious diets early in childhood will have a positive effect on one's IQ later in life .
Select the correct answer. Sarah wants to print copies of her artwork. At the local print shop, it costs her $1 to make 5 copies and $5 to make 25 copies. How much would it cost Sarah to make 100 copies? A. $15 B. $20 C. $25 D. $30
Answers
$1 = 5copies means
$5 = 25 copies obviously
then
$x = 100 copies
100 / 5 = $x
so she needs
$20
The cost of printing 100 copies of artwork is $20.
What is a unitary method?A unitary method is a mathematical way of obtaining the value of a single unit and then deriving any no. of given units by multiplying it with the single unit.
Suppose 2 pens cost $10, So the cost of 1 pen is (10/2) = $5.
From this unitary cost of pens, we can determine the cost of any no. of pens by multiplying the unit cost by the no. of pens.
Given, The cost of printing 5 artworks is $1.
∴ The cost of printing 100 copies is $(100/5),
= $20.
learn more about the unitary method here :
https://brainly.com/question/22056199
#SPJ2
How would 2X - 2Y - 6 = 0 be
written in slope-intercept form?
A. 2X - 2Y = 6
B. -2Y = 2X = 6
C. Y=X - 3
D. Y = -2X - 3
E. Y = x + 3
Answers
Answer:
D. Y= -2x - 3
Step-by-step explanation:
The reason the answer is D is because it is the reverse form of standard. D shows that the form of slope-intercept for is y=mx + b.
Answer:
C. Y=X - 3
Step-by-step explanation:
[tex]2X - 2Y - 6 = 0\\\mathbf{y=mx+b}\:\mathrm{is\:the\:slope\:intercept\:form\:of\:a\:line\:where}\: \mathbf{m}\:\mathrm{is\:the\:slope\:and}\:\mathbf{b}\:\mathrm{is\:the}\:\mathbf{y}\:\mathrm{intercept}\\\mathrm{For\:a\:line\:in\:the\:form\:of\:}\mathbf{y=mx+b}\mathrm{,\:the\:slope\:is}\:\mathbf{m}\:\mathrm{and}\:\mathbf{y}\:\mathrm{intercept\:is}\:\mathbf{b}\\\\Y=X-3[/tex]
A certain article indicates that in a sample of 1,000 dog owners, 680 said that they take more pictures of their dog than of their significant others or friends, and 490 said that they are more likely to complain to their dog than to a friend. Suppose that it is reasonable to consider this sample as representative of the population of dog owners.
(a) Construct a 90% confidence interval for the proportion of dog owners who take more pictures of their dog than of their significant others or friends. (Use a table or technology. Round your answers to three decimal places.)
(______),(_________)
(b) Construct a 95% confidence interval for the proportion of dog owners who are more likely to complain to their dog than to a friend. (Use a table or technology. Round your answers to three decimal places.)
(_______),(_______)
Answers
Answer: a) a 90% confidence interval for the proportion of dog owners who take more pictures of their dog than of their significant others or friends is (0.656,0.704).
b) a 95% confidence interval for the proportion of dog owners who are more likely to complain to their dog than to a friend is (0.459,0.521).
Step-by-step explanation:
Confidence interval for a population proportion is given by:-
[tex]\hat{p}\pm z(\sqrt{\dfrac{\hat{p}(1-\hat{p})}{n}})[/tex]
, where [tex]\hat{p}[/tex] = sample proportion , n= sample size, z= critical z-value.
As per given,
a) n=1000
Sample proportion of dog owners say they take more pictures of their dog than of their significant others or friends =[tex]\hat{p}=\dfrac{680}{1000}=0.68[/tex]
critical value for 90% confidence = 1.645 [By table]
A 90% confidence interval for the proportion of dog owners who take more pictures of their dog than of their significant others or friends.
[tex]0.68\pm (1.645)\sqrt{\dfrac{0.68(1-0.68)}{1000}}\\\\\approx0.68\pm0.024=(0.68-0.024,0.68+0.024)=(0.656,0.704)[/tex]
Hence, a 90% confidence interval for the proportion of dog owners who take more pictures of their dog than of their significant others or friends is (0.656,0.704).
b) Sample proportion of dog owners say they are more likely to complain to their dog than to a friend =[tex]\hat{p}=\dfrac{490}{1000}=0.49[/tex]
critical value for 95% confidence = 1.96 [By table]
A 95% confidence interval for the proportion of dog owners who are more likely to complain to their dog than to a friend:
[tex]0.49\pm (1.96)\sqrt{\dfrac{0.49(1-0.49)}{1000}}\\\\\approx0.49\pm0.031=(0.49-0.031,0.49+0.031)=(0.459,0.521)[/tex]
Hence, a 95% confidence interval for the proportion of dog owners who are more likely to complain to their dog than to a friend is (0.459,0.521).
i will give brainliest and 50 points pls help ASP
pls can u show how to work this out thx !!! : )
its a simultaneous equation
Answers
Answer:
x = 3
y = -2
Step-by-step explanation:
Given:
8x - 3y = 30 ..................(1)
3x + y = 7 .......................(2)
Eliminate y by adding (1)+3*(2)
8x-3y + 3*( 3x+y) = 30 + 3*7
8x + 9x -3y + 3y = 51
17x = 51
x = 3 .....................(3)
substitute (3) in (2)
3(3) + y = 7
y = 7-9 = -2
y = -2 ....................(4)
Answer:
Step-by-step explanation:
[tex]8x-3y=30\\y=7-3x\\\\8x-3(7-3x)=30\\8x-21+9x=30\\17x=51\\x=3\\\\y=7-3(3)\\y=7-9\\y=-2[/tex]
-15≤-3c plz helpppppppppp
Answers
Answer:
5 ≥ c
Step-by-step explanation:
-15≤-3c
Divide each side by -3, remembering to flip the inequality
-15/-3 ≤ -3c/-3
5 ≥ c
Answer:
c ≤ 5
Step-by-step explanation:
Since you have to divide both sides of the equation by a negative number, you have to flip the equality sign.
-15 ≤ -3c
(-15)/(-3) ≤ (-3c)/-3
5 ≥ c
c ≤ 5
A copy machine makes 153 copies in 4 minutes 15 seconds how many copies does it make per minute
Answers
Answer:
36 copies.
Step-by-step explanation:
4mins 15 seconds is the same as 4+1/4 minsutes. Since 1 minute is less than 4+1/4minutes and 4+1/4 minutes produces 153 copies. 1 minute will produce less.
(1÷4+1/4)×153
= 36 copies.
Change the time into seconds so they’ll be in the same unit, (4*60) + 15= 255. Do cross multiplication,
153. 255
? 60
(153*60) / 255= 36
Please help!! Which inequality is graphed on the coordinate plane?
Answers
Answer:
The correct answer that corresponds with that graph is B: y ≤-3x+2.
Step-by-step explanation:
1) First we need to figure out what kind of symbol the line is, greater or less than equations (< , >) then the line are dotted,and if its greater than or equal to or less than or equal to equations ( ≤, ≥) since the line are solid.
2) Now we need to figure out which side should be shaded, if the symbol is a less than or a less than or equal to then the shaded side should be on the left, if the symbol is a greater than or a greater than or equal then the shaded side should be on the right.
In this case we have a solid line and a shaded left side which mean the symbol that been used here is a less than or equal to symbol ( ≤ ).
So our answer is B: y ≤-3x+2.
Remember:
- greater or less than equations (< , >) = dotted line
- greater than or equal to or less than or equal to equations ( ≤, ≥) = solid line
- less than or a less than or equal to = shaded left side
- greater than or greater than or equal to = shaded right side
If the triangle on the grid below is translated by using the rule (x, y) right-arrow (x + 5, y minus 2), what will be the coordinates of B prime?
Answers
Answer:
Option (2)
Step-by-step explanation:
If a point having coordinates (x, y) is translated by 'h' units right and 'k' units down,
New coordinates of the point will be,
(x, y) → [(x + h), (y - k)]
Coordinates of the vertices of the given triangle ABC are,
A(-1, 0), B(-5, 0) and C(-1, 2)
If this triangle is shifted 5 units right and 2 units down then the coordinates of point B will be,
B(-5, 0) → B'[(-5 + 5), (0 -2)]
→ B'(0, -2)
Therefore, coordinates of vertex B' will be (0, -2).
Option (2) will be the answer.
Answer:
(0,-2) is Correct
Have a Blessed day!
What are some key words used to note addition operations?
Answers
Answer:
The correct answer is
For addition, Caulleen used the words total, sum, altogether, and increase. But we could also have used the words combine, plus, more than, or even just the word "and". For subtraction, Caulleen used the words, fewer than, decrease, take away, and subtract. We also could have used less than, minus, and difference.
Step-by-step explanation:
hope this helps u!!!
Linda, Reuben, and Manuel have a total of $70 in their wallets. Reuben has $10 more than Linda. Manuel has 2 times what Linda has. How much does each have? Amount in Linda's wallet: $ Amount in Reuben's wallet: $ Amount in Manuel's wallet:
Answers
Answer:
Linda has $15Reuben has $25Manuel has $30Step-by-step explanation:
Together, they have 4 times what Linda has, plus $10. So, Linda has 1/4 of $60 = $15.
Linda has $15
Reuben has $25 . . . . . . $10 more than Linda
Manuel has $30 . . . . . . twice what Linda has
From which sphere of earth did this food did this food originate
Answers
Answer:
I'm not entirely sure what you are asking, could you comment on this answer the full question so I can edit this question to provide you an answer?
Answer: biosphere
Step-by-step explanation:
I am not sure what picture you are looking at but if it is 3 barbeque chicken legs in one image than this is your answer. The reason being that chickens can only be found on land and the land is considered part of the biosphere because bio = life
The letters G, E, N, I, D, S are placed in a bag. What is the probability that the letters are randomly pulled from the bag in the order that spells DESIGN?
Answers
Answer as a fraction = 1/5040
Answer in decimal form (approximate) = 0.000198
Answer in percentage form (approximate) = 0.0198%
=========================================================
Explanation:
There is only one ordering of the letters to get DESIGN out of 5040 different permutations. The 5040 comes from the fact that 7*6*5*4*3*2*1 = 5040. In shorthand notation, use factorials to say 7! = 5040. Notice how we started with 7 and counted down until reaching 1, multiplying all along the way. You could use the nPr permutation formula to get the same result of 5040 (use n = 7 and r = 7).
So because we have 1 way to order the letters (getting DESIGN) out of 5040 ways total, this means the probability is the fraction 1/5040. Use your calculator to find that 1/5040 = 0.000198 approximately. Move the decimal over 2 spots to the right to convert 0.000198 to 0.0198%
The equation of the line of best fit is y=15.621x+8.83 Based on the line of best fit, Approximately how many pages are predicted To be in a book with eight chapters
Answers
Answer:
[tex] y = 15.621x +8.83[/tex]
We assume that y represent the number of pages predicted and x the number of chapters.
And we want to find the predicted value for a book of x =8 chapters. S replacing we got:
[tex] y = 15.621*8 + 8.83= 133.798[/tex]
And we can conclude that approximately we would have between 133 and 134 pages for a book of 8 chapters
Step-by-step explanation:
For this case we have the following model given:
[tex] y = 15.621x +8.83[/tex]
We assume that y represent the number of pages predicted and x the number of chapters.
And we want to find the predicted value for a book of x =8 chapters. S replacing we got:
[tex] y = 15.621*8 + 8.83= 133.798[/tex]
And we can conclude that approximately we would have between 133 and 134 pages for a book of 8 chapters
If the code for CAB is DEK, what is the code for BED?
Answers
Answer:
CIM
Step-by-step explanation:
C is the 3rd letter of the alphabet, A is the 1st, and B is the 2nd.
CAB = 3,1,2
Repeating for DEK:
DEK = 4,5,11
Comparing:
4−3 = 1
5−1 = 4
11−2 = 9
BED = 2,5,4, so adding the corresponding numbers:
2+1 = 3
5+4 = 9
4+9 = 13
So the code is CIM.
The code for BED is CIM. A further explanation is below.
As we know that,
"C" is the third letter of the alphabet"A" is the first letter of the alphabet."B" is the Second letter of the alphabet.then,
→ CIB = 3, 1, 2
Same as above,
→ DEK = 4, 5, 11
By comparing the values, we get
[tex]4-3 =1[/tex][tex]5-1 =4[/tex][tex]11-2 =9[/tex]Same as above,
→ BED = 2, 5, 4
then,
[tex]2+1=3[/tex][tex]5+4 =9[/tex][tex]4+9 =13[/tex]Thus the above approach is appropriate.
Learn more:
https://brainly.com/question/18804431
Lacey's mom makes her a birthday cake in the shape of an "L" . Lacey loves frosting, so her mom covers the entire outside of the cake in frosting, even the bottom of the cake. How much space does Lacey's mom cover in frosting? cm2\text{cm}^2cm2start text, c, m, end text, squared
Answers
Answer:
1360cm²
Step-by-step explanation:
Since the shape of the cake is in L shape, we can divide the cake in to rectangles..
The amount of space covered by the frosting = The sum of the areas of the sides that we can find in this L shaped cake diagram.
The sides of this cake, are shaped like a rectangle.
Hence, Area of a Rectangle = Length × Width
a) Side 1 = Rectangle on the left
Area of a Rectangle = Length × Breadth
Length = 30cm
Breadth =10cm
Area = 30 × 10 = 300cm²
Since we have another side with this measurement/ dimensions also,
Side 2 = 300cm²
Side 3 = The front face of the cube by the right
Area of a Rectangle = Length × Breadth
Length = 22cm - 10cm = 12cm
Breadth =10cm
Area = 12 × 10 = 120cm²
Likewise, we have the another side with the same dimensions as well
Hence, Side 4 = 120cm²
Side 5
30 × 5 = 150cm²
Side 6
10 × 5 = 50cm²
Side 7
20 × 5 = 100cm²
Side 8
22cm × 5 cm = 110cm²
Side 9
10cm × 5cm = 50cm²
Side 10
12cm × 5cm = 60cm²
The amount of space covered by the frosting = Area of Sides( 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= (300 + 300 + 120 + 120 + 150 + 50 + 100 + 110 + 50 + 60) cm²
= 1360cm²
What is the solution of log3(3x+2)= log3 (4x-6)?
Answers
Answer:
x=8 i got it right on my homework on khan academy
Step-by-step explanation:
Answer: Using logarithms to solve you will get x = 8
HELP number 12 pls i do nor have long more
Answers
Answer:
Dian has $250 originally.
Step-by-step explanation:
Let the total money Dian has originally = $S
Dian gave [tex]\frac{2}{5}[/tex] of her total money to Justin,
Money given to Justin = [tex]\frac{2}{5}(\text{S})[/tex]
Money left with Dian = S - [tex]\frac{2}{5}(\text{S})[/tex]
= [tex]\frac{\text{5S-2S}}{5}[/tex]
= [tex]\frac{3S}{5}[/tex]
Since Dian has $150 left then the equation will be,
[tex]\frac{3S}{5}=150[/tex]
S = [tex]\frac{150\times 5}{3}[/tex]
S = $250
Therefore, Dian has $250 originally.
State the degrees of freedom error in each of the following tests. (a) A consultant measures job satisfaction in a sample of 14 supervisors, 14 managers, and 14 executives at a local firm. (b) A researcher tests how nervous public speakers get in front of a small, medium, or large audience. Ten participants are randomly assigned to each group. (c) A high school counselor has 8 students in each of five classes rate how much they like their teacher.
Answers
Answer:
.
Step-by-step explanation:
How many solutions does the following equation have? 14(z+3)=14z+21
Answers
Answer:
No solutions
Step-by-step explanation:
14(z + 3) = 14z + 21
Expand brackets.
14z + 42 = 14z + 21
Subtract 14z on both sides.
42 = 21
There are no solutions.
Answer:
No solution
Step-by-step explanation:
First, We have to simplify the right side.
Distribute 14, 14z+42.
Now the equation stands as 14z+42=14z+21
Subtract 14z from both sides,
this makes it 42=21.
We know when the solution is #=#, our answer is no solution.
There is a stack of 10 cards, each given a different number from 1 to 10. Suppose we select a card randomly from the stack, replace it, and then randomly select another card. What is the probability that the first card is an odd number and the second card is greater than 7
Answers
====================================================
Explanation:
Here's our sample space
{1,2,3,4,5,6,7,8,9,10}
This is the set of all possible outcomes.
We see that {1,3,5,7,9} are odd. We have 5 odd numbers out of 10 total. The probability of getting an odd number is therefore 5/10 = 1/2. Let A = 1/2 as we'll use it later.
After we select the first card and put it back (or replace it with a copy), the stack of cards is the same as before we made that first selection. So the sample space hasn't changed. The set of values greater than 7 is {8,9,10}. We have 3 items in here out of 10 total. The probability of getting a value larger than 7 is 3/10. Let B = 3/10.
Multiply the values of A and B to get the answer
A*B = (1/2)*(3/10) = 3/20
This represents the probability of getting an odd number on the first selection, and a second card that is larger than 7. This only applies if a replacement is made on the first card. Otherwise, 3/10 would be different.
Eighty percent of the light aircraft that disappear while in flight in a certain country are subsequently discovered. Of the aircraft that are discovered, 63% have an emergency locator, whereas 89% of the aircraft not discovered do not have such a locator. Suppose a light aircraft has disappeared. (Round your answers to three decimal places.) (a) If it has an emergency locator, what is the probability that it will not be discovered? (b) If it does not have an emergency locator, what is the probability that it will be discovered?
Answers
Answer:
a) P(B'|A) = 0.042
b) P(B|A') = 0.625
Step-by-step explanation:
Given that:
80% of the light aircraft that disappear while in flight in a certain country are subsequently discovered
Of the aircraft that are discovered, 63% have an emergency locator,
whereas 89% of the aircraft not discovered do not have such a locator.
From the given information; it is suitable we define the events in order to calculate the probabilities.
So, Let :
A = Locator
B = Discovered
A' = No Locator
B' = No Discovered
So; P(B) = 0.8
P(B') = 1 - P(B)
P(B') = 1- 0.8
P(B') = 0.2
P(A|B) = 0.63
P(A'|B) = 1 - P(A|B)
P(A'|B) = 1- 0.63
P(A'|B) = 0.37
P(A'|B') = 0.89
P(A|B') = 1 - P(A'|B')
P(A|B') = 1 - 0.89
P(A|B') = 0.11
Also;
P(B ∩ A) = P(A|B) P(B)
P(B ∩ A) = 0.63 × 0.8
P(B ∩ A) = 0.504
P(B ∩ A') = P(A'|B) P(B)
P(B ∩ A') = 0.37 × 0.8
P(B ∩ A') = 0.296
P(B' ∩ A) = P(A|B') P(B')
P(B' ∩ A) = 0.11 × 0.2
P(B' ∩ A) = 0.022
P(B' ∩ A') = P(A'|B') P(B')
P(B' ∩ A') = 0.89 × 0.2
P(B' ∩ A') = 0.178
Similarly:
P(A) = P(B ∩ A ) + P(B' ∩ A)
P(A) = 0.504 + 0.022
P(A) = 0.526
P(A') = 1 - P(A)
P(A') = 1 - 0.526
P(A') = 0.474
The probability that it will not be discovered given that it has an emergency locator is,
P(B'|A) = P(B' ∩ A)/P(A)
P(B'|A) = 0.022/0.526
P(B'|A) = 0.042
(b) If it does not have an emergency locator, what is the probability that it will be discovered?
The probability that it will be discovered given that it does not have an emergency locator is:
P(B|A') = P(B ∩ A')/P(A')
P(B|A') = 0.296/0.474
P(B|A') = 0.625
If Joe drives 50 mph for 0.5 hours and then 60 mph for 1.5 hours, then how far did he drive?
Answers
Answer:
115 mi
Step-by-step explanation:
speed = distance/time
distance = speed * time
0.5 hours at 50 mph
distance = 50 mph * 0.5 h = 25 mi
1.5 hours at 60 mph
distance = 60 mph * 1.5 h = 90 mi
total distance = 25 mi + 90 mi = 115 mi
Solve the equation for x 5x-(4x-1)=2 A 1/9 B -1 C -1/9 D 1
Answers
Answer:
D
Step-by-step explanation:
A magazine article states that the mean weight of one-year-old boys is the same as that of one-year-old girls. Does the confidence interval contradict this statement? The confidence interval this statement
Answers
Answer:
Yes, the confidence interval contradict this statement.
Step-by-step explanation:
The complete question is attached below.
The data provided is:
[tex]n_{1}=318\\n_{2}=297\\\bar x_{1}=25\\\bar x_{2}=24.1\\s_{1}=3.6\\s_{2}=3.8[/tex]
Since the population standard deviations are not provided, we will use the t-confidence interval,
[tex]CI=(\bar x_{1}-\bar x_{2})\pm t_{\alpha/2, (n_{1}+n_{2}-2)}\cdot s_{p}\cdot\sqrt{\frac{1}{n_{1}}+\frac{1}{n_{2}}}[/tex]
Compute the pooled standard deviation as follows:
[tex]s_{p}=\sqrt{\frac{(n_{1}-1)s_{1}^{2}+(n_{2}-1)s_{2}^{2}}{n_{1}+n_{2}-2}}=\sqrt{\frac{(318-1)(3.6)^{2}+(297-1)(3.8)^{2}}{318+297-2}}=2.9723[/tex]
The critical value is:
[tex]t_{\alpha/2, (n_{1}+n_{2}-2)}=t_{0.05/2, (318+297-2)}=t_{0.025, 613}=1.962[/tex]
*Use a t-table.
The 95% confidence interval is:
[tex]CI=(\bar x_{1}-\bar x_{2})\pm t_{\alpha/2, (n_{1}+n_{2}-2)}\cdot s_{p}\cdot\sqrt{\frac{1}{n_{1}}+\frac{1}{n_{2}}}[/tex]
[tex]=(25-24.1)\pm 1.962\times 2.9723\times \sqrt{\frac{1}{318}+\frac{1}{297}}\\\\=0.90\pm 0.471\\\\=(0.429, 1.371)\\\\\approx (0.43, 1.37)[/tex]
The 95% confidence interval for the difference between the mean weights is (0.43, 1.37).
To test the magazine's claim the hypothesis can be defined as follows:
H₀: There is no difference between the mean weight of 1-year old boys and girls, i.e. [tex]\mu_{1}-\mu_{2}=0[/tex].
Hₐ: There is a significant difference between the mean weight of 1-year old boys and girls, i.e. [tex]\mu_{1}-\mu_{2}\neq 0[/tex].
Decision rule:
If the confidence interval does not consists of the null value, i.e. 0, the null hypothesis will be rejected.
The 95% confidence interval for the difference between the mean weights does not consists the value 0.
Thus, the null hypothesis will be rejected.
Conclusion:
There is a significant difference between the mean weight of 1-year old boys and 1-year old girls.
Suppose the sediment density (g/cm) of a randomly selected specimen from a certain region is normally distributed with mean 2.68 and standard deviation 0.92.
A. If a random sample of 25 specimens is selected, what is theprobability that the sample average sediment density is at most3.00? Between 2.68 and 3.00
B. How large a sample size would be required to ensure thatthe first probability in part (a) is at least .99 ?
Answers
Answer:
The sample size must be 45 large enough that would ensure that the first probability in part (a) is at least 0.99.
Step-by-step explanation:
We are given that the sediment density (g/cm) of a randomly selected specimen from a certain region is normally distributed with mean 2.68 and standard deviation 0.92.
Let [tex]\bar X[/tex] = sample average sediment density
The z-score probability distribution for the sample mean is given by;
Z = [tex]\frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }[/tex] ~ N(0,1)
where, [tex]\mu[/tex] = population mean = 2.68
[tex]\sigma[/tex] = population standard deviation = 0.92
n = sample of specimens = 25
(a) The probability that the sample average sediment density is at most 3.00 is given by = P([tex]\bar X[/tex] [tex]\leq[/tex] 3.00)
P([tex]\bar X[/tex] [tex]\leq[/tex] 3.00) = P( [tex]\frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }[/tex] [tex]\leq[/tex] [tex]\frac{3.00-2.68}{\frac{0.92}{\sqrt{25} } }[/tex] ) = P(Z [tex]\leq[/tex] 1.74) = 0.9591
The above probability is calculated by looking at the value of x = 1.74 in the z table which has an area of 0.9591.
Also, the probability that the sample average sediment density is between 2.68 and 3.00 is given by = P(2.68 < [tex]\bar X[/tex] < 3.00)
P(2.68 < [tex]\bar X[/tex] < 3.00) = P([tex]\bar X[/tex] < 3.00) - P([tex]\bar X[/tex] [tex]\leq[/tex] 2.68)
P([tex]\bar X[/tex] < 3.00) = P( [tex]\frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }[/tex] < [tex]\frac{3.00-2.68}{\frac{0.92}{\sqrt{25} } }[/tex] ) = P(Z < 1.74) = 0.9591
P([tex]\bar X[/tex] [tex]\leq[/tex] 2.68) = P( [tex]\frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }[/tex] [tex]\leq[/tex] [tex]\frac{2.68-2.68}{\frac{0.92}{\sqrt{25} } }[/tex] ) = P(Z [tex]\leq[/tex] 0) = 0.50
The above probability is calculated by looking at the value of x = 1.74 and x = 0 in the z table which has an area of 0.9591 and 0.50.
Therefore, P(2.68 < [tex]\bar X[/tex] < 3.00) = 0.9591 - 0.50 = 0.4591.
(b) Now, we have to find a sample size that would ensure that the first probability in part (a) is at least 0.99, that is;
P([tex]\bar X[/tex] [tex]\leq[/tex] 3.00) [tex]\geq[/tex] 0.99
P( [tex]\frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }[/tex] [tex]\leq[/tex] [tex]\frac{3.00-2.68}{\frac{0.92}{\sqrt{n} } }[/tex] ) [tex]\geq[/tex] 0.99
P(Z [tex]\leq[/tex] [tex]\frac{3.00-2.68}{\frac{0.92}{\sqrt{n} } }[/tex] ) [tex]\geq[/tex] 0.99
Now, in the z table; the critical value of x which has an area of at least 0.99 is given by 2.3263, that is;
[tex]\frac{3.00-2.68}{\frac{0.92}{\sqrt{n} } }=2.3263[/tex]
[tex]\sqrt{n} } }=\frac{ 2.3263\times 0.92}{0.32}[/tex]
[tex]\sqrt{n} } }=6.69[/tex]
n = 44.76 ≈ 45 {By squaring both sides}
Hence, the sample size must be 45 large enough that would ensure that the first probability in part (a) is at least 0.99.
Use identities to find values of the sine and cosine functions of the function for the angle measure
a. theta, given that cos2theta=28/53 and 0theta < theta < 90degrees
b. 2theta, given sin theta= - sqrt 7 over 5 and cos theta > 0
c. 2x, given tan x=2 and cos x<0
Answers
Answer:
Step-by-step explanation:
a) Given cos2theta=28/53 and 0degrees< theta < 90degrees
From cos2theta=28/53
[tex]2\theta = cos^{-1}\frac{28}{53}[/tex]
[tex]2\theta = cos^{-1}0.5283\\ \\2\theta = 58.12\\\\Dividing\ both \ sides\ by \ 2\\\\\frac{2\theta}{2} = \frac{58.12}{2}\\ \\\theta = 29.06^0[/tex]
b) Given
[tex]sin\theta = \frac{-\sqrt{7} }{5} \\\\\theta = sin^{-1} \frac{-\sqrt{7} }{5}\\\\\\\theta = sin^{-1} \frac{-2.6458}{5}\\\\\theta = sin^{-1} -0.5292\\\\\theta = -31.95^0[/tex]
If cos theta [tex]\gneq[/tex] 0, this means we need to look for the quadrant where sin is negative and cos is positive. That will be the fourth quadrant. In the fourth quadrant, theta = 360 - 31.95° = 328.05°
2theta = 2 * 328.05
2theta = 656.1°
c) Given tan x=2 and cos x<0, lets find the angle of x first.
If tan x = 2
x = tan^-1 2
x = 63.4°
Sine cos is less than 0, then we need to find the angle of x where tan is positive and cos is negative. That will be the third quadrant. In the third quadrant, ew value of x = 180+63.4
x = 243.4°
Since we are to find 2x,
2x = 2(243.4)
2x = 486.8°