We draw a random sample of size 25 from a normal population with variance 2.4. If the sample mean is 12.5, what is a 99% confidence interval for the population mean?

Answer:

1.35

Step-by-step explanation:

next cube above 540 is 729

to get to 729: 729 / 540 = 1.35

n = 1.35

Answer:

  28, 30, 32

Step-by-step explanation:

Their average will be 90/3 = 30. That is the middle integer.

The three integers are 28, 30, 32.

_____

Comment on the working

It often works well to use the average value when working consecutive integer problems. The average of an odd number of consecutive integers is the middle one. The average of an even number of consecutive integers is halfway between the middle two.

Answer:

D

Step-by-step explanation:

The graph above is your graph.

As x increase, y decreases

As x decrease, y increases.

However, there is a small portion of the graph where both x and y were positive.

But I'm guessing it should be D.

Answer:

D

Step-by-step explanation:

[tex]f(x)=-x^3+2x^2-x+3[/tex]

As the highest power is 3, it is odd, as [tex]x[/tex] approaches to [tex]-\infty[/tex] [tex]y[/tex] approaches to [tex]\infty[/tex]

First, we have [tex]x \rightarrow-\infty[/tex], [tex]y \rightarrow \infty[/tex]

Plotting the graph, you can easily conclude the answer to the question.

And as [tex]x \rightarrow \infty[/tex], [tex]y \rightarrow -\infty[/tex]

Answer:

$10 to rent shoes for 9 people

Step-by-step explanation:

Total amount of the party = $140

A bowling lane = $50

$140 - $50 = $90

$90 divided by 9 = 10

$10 to rent shoes for 9 people

Answer:

23) x ≥ -140.

24) k > -9.

25) v ≥ 9.

26) m > 16.

Step-by-step explanation:

23) -14 ≤ [tex]\frac{x}{10}[/tex]

[tex]\frac{x}{10}[/tex] ≥ -14

x ≥ -140

Since it is a ≥ sign, you will put a shaded circle at -140, and the line will stretch infinitely to the right of the circle.

24) -20 < k - 11

k - 11 > -20

k > -9

Since it is a > sign, you will put a non-shaded circle at -9, and the line will stretch infinitely to the right of the circle.

25) -6v ≤ 54

6v ≥ 54

v ≥ 9

Since it is a ≥ sign, you will put a shaded circle at 9, and the line will stretch infinitely to the right of the circle.

26) 8 < [tex]\frac{m}{2}[/tex]

[tex]\frac{m}{2}[/tex] > 8

m > 16

Since it is a > sign, you will put a non-shaded circle at 16, and the line will stretch infinitely to the right of the circle.

Answer

Step-by-step explanation:

Answer:

See the argument below

Step-by-step explanation:

I will give the argument in symbolic form, using rules of inference.

First, let's conclude c.

(1)⇒a  by simplification of conjunction

a⇒¬(¬a) by double negation

¬(¬a)∧(2)⇒¬(¬c) by Modus tollens

¬(¬c)⇒c by double negation

Now, the premise (5) is equivalent to ¬d∧¬h which is one of De Morgan's laws. From simplification, we conclude ¬h. We also concluded c before, then by adjunction, we conclude c∧¬h.

An alternative approach to De Morgan's law is the following:

By contradiction proof, assume h is true.

h⇒d∨h by addition

(5)∧(d∨h)⇒¬(d∨h)∧(d∨h), a contradiction. Hence we conclude ¬h.  

Answer:

(x – 4)^2 + (y + 7)^2 = 16

Step-by-step explanation:

The formula of a circle is:

(x – h)^2 + (y – k)^2 = r^2

(h, k) represents the coordinates of the center of the circle

r represents the radius of the circle

If you plug in the given information, you get:

(x – 4)^2 + (y – (-7))^2 = 4^2

which simplifies into:

(x – 4)^2 + (y + 7)^2 = 16

Answer:  203,280

Step-by-step explanation:

Given: A catering service offers 11 appetizers, 12 main courses, and 8 desserts.

Number of combinations of choosing r things out of n = [tex]^nC_r=\dfrac{n!}{r!(n-r)!}[/tex]

A customer is to select 9 appetizers, 2 main courses, and 3 desserts for a banquet.

Total number of ways to do this: [tex]^{11}C_9\times ^{12}C_2\times^{8}C_3[/tex]

[tex]=\dfrac{11!}{9!2!}\times\dfrac{12!}{2!10!}\times\dfrac{8!}{3!5!}\\\\=\dfrac{11\times10}{2}\times\dfrac{12\times11}{2}\times\dfrac{8\times7\times6}{3\times2}\\\\= 203280[/tex]

hence , this can be done in 203,280 ways.

Answer: 6 / √26

Step-by-step explanation:

Given that f(x, y, z) = xe^y + ye^z + ze^x

so first we compute the gradient vector at (0, 0, 0)

Δf ( x, y, z ) = [ e^y + ze^x,  xe^y + e^z,  ye^z + e^x ]

Δf ( 0, 0, 0 ) = [ e⁰ + 0(e)⁰, 0(e)⁰ + e⁰, 0(e)⁰ + e⁰ ] = [ 1+0 , 0+1, 0+1 ] = [ 1, 1, 1 ]

Now we were also given that  V = < 4, 3, -1 >

so ║v║ = √ ( 4² + 3² + (-1)² )

║v║ = √ ( 16 + 9 + 1 )

║v║ = √ 26

It must be noted that "v"  is not a unit vector but since ║v║ = √ 26, the unit vector in the direction of "V" is ⊆ = ( V / ║v║)

so

⊆ =  ( V / ║v║) = [ 4/√26, 3/√26, -1/√26 ]

therefore by equation   D⊆f ( x, y, z ) = Δf ( x, y, z ) × ⊆

D⊆f ( x, y, z ) = Δf ( 0, 0, 0 ) × ⊆ = [ 1, 1, 1 ] × [ 4/√26, 3/√26, -1/√26 ]

= ( 1×4 + 1×3 -1×1 ) / √26

= (4 + 3 - 1) / √26

= 6 / √26

Answer: [tex]S=0.087p[/tex] .

Step-by-step explanation:

Equation for direct proportion:

y=kx

, where x= independent variable ,

y=dependent variable.

k= proportionality constant

Here, State sales tax S  is directly proportional to retail price p.

Also, dependent variable= S,  independent variable =p

Required equation: S= kp

Put S= 12.32 and x= 142

[tex]S=12.32=k(142)\\\\\Rightarrow\ k=\dfrac{12.32}{142}\approx0.087[/tex]

Hence, the required equation is [tex]S=0.087p[/tex] .

Answer:

linear

Step-by-step explanation:

Power and chain rule (where the power rule kicks in because [tex]\sqrt x=x^{1/2}[/tex]):

[tex]\left(\sqrt{\dfrac{\cos(2x)}{1+\sin(2x)}}\right)'=\dfrac1{2\sqrt{\frac{\cos(2x)}{1+\sin(2x)}}}\left(\dfrac{\cos(2x)}{1+\sin(2x)}\right)'[/tex]

Simplify the leading term as

[tex]\dfrac1{2\sqrt{\frac{\cos(2x)}{1+\sin(2x)}}}=\dfrac{\sqrt{1+\sin(2x)}}{2\sqrt{\cos(2x)}}[/tex]

Quotient rule:

[tex]\left(\dfrac{\cos(2x)}{1+\sin(2x)}\right)'=\dfrac{(1+\sin(2x))(\cos(2x))'-\cos(2x)(1+\sin(2x))'}{(1+\sin(2x))^2}[/tex]

Chain rule:

[tex](\cos(2x))'=-\sin(2x)(2x)'=-2\sin(2x)[/tex]

[tex](1+\sin(2x))'=\cos(2x)(2x)'=2\cos(2x)[/tex]

Put everything together and simplify:

[tex]\dfrac{\sqrt{1+\sin(2x)}}{2\sqrt{\cos(2x)}}\dfrac{(1+\sin(2x))(-2\sin(2x))-\cos(2x)(2\cos(2x))}{(1+\sin(2x))^2}[/tex]

[tex]=\dfrac{\sqrt{1+\sin(2x)}}{2\sqrt{\cos(2x)}}\dfrac{-2\sin(2x)-2\sin^2(2x)-2\cos^2(2x)}{(1+\sin(2x))^2}[/tex]

[tex]=\dfrac{\sqrt{1+\sin(2x)}}{2\sqrt{\cos(2x)}}\dfrac{-2\sin(2x)-2}{(1+\sin(2x))^2}[/tex]

[tex]=-\dfrac{\sqrt{1+\sin(2x)}}{\sqrt{\cos(2x)}}\dfrac{\sin(2x)+1}{(1+\sin(2x))^2}[/tex]

[tex]=-\dfrac{\sqrt{1+\sin(2x)}}{\sqrt{\cos(2x)}}\dfrac1{1+\sin(2x)}[/tex]

[tex]=-\dfrac1{\sqrt{\cos(2x)}}\dfrac1{\sqrt{1+\sin(2x)}}[/tex]

[tex]=\boxed{-\dfrac1{\sqrt{\cos(2x)(1+\sin(2x))}}}[/tex]

Answer:

"B. about half the days in march had average temperatures either below 60 or above 73 degrees"

Step-by-step explanation:

To answer this question, note that a box plot is usually divided into quartiles, each representing approximately 25% each.

In the box plot above,

*about 25% (Q1) represents days with temperature of 60° and below. This is about ¼ of the days in March.

*About 25% (Q2) represents days with temperature between 61° and 68°. That's about ¼ of the days in March

*About 25% (Q3) represents days with temperature between 70° and 73°. That's about ¼ of the days in March

*About 25% (Q4) represents days with temperature between 74° and 82°. That's about ¼ of the days in March

*Coldest day in March has a temperature of 54°

*Hottest day in March is 82°

From the options given, the only statement that is true is "B. about half the days in march had average temperatures either below 60 or above 73 degrees"

¼ of the Days in March has temperatures below 60° (Q1), while ¼ of the days in March has temperatures above 73° (Q4). Therefore, ¼+¼ = ½ of the days in March having average temperatures either below 60 or above 73 degrees.

Answer:

b

Step-by-step explanation:

About half of the days in March had average temperatures either below 60 or above 73 degrees.

Answer:

The integers are the numbers such that:

- The distance between consecutive integers is always of 1 unit and the integer numbers only have zeros after the decimal point, such that the set is: Z = {..., 0, 1, 2, 3, 4, ......}

74) No digits after the decimal point, so this is an integer.

3.49) we have digits after the decimal point, so this is not an integer.

4/7) 4 is smaller than 7, so 4/7 is smaller than one and larger than zero,

one and zero are consecutive integer numbers, so 4/7 can not be an integer number.

You also can solve the division and find that the quotient has digits after the decimal point.

148.29) This number has digits after the decimal point, so this is not an integer number.

8/1) here we have 8 divided by one, we know that:

8/1 = 8

8 has no digits after the decimal point, so this is an integer.

Answer:

3 feet

Step-by-step explanation:

To find x, we can write the following equation:

x + 4 + x = 10

2x + 4 = 10

2x = 6

x = 3 feet

Answer:

[tex]\large \boxed{\sf \text{The rate of the boat is } 53 \ km/h \text{, the rate of the current is }8\ km/h \ \ }[/tex]

Step-by-step explanation:

Hello, let's note v the rate of the boat and r the rate of the current. We can write the following

[tex]\dfrac{135}{v-r}=3=\dfrac{183}{v+r}[/tex]

It means that

[tex]135(v+r)=183(v-r)\\\\135 v + 135r=183v-183r\\\\\text{ *** We regroup the terms in v on the right and the ones in r to the left***}\\\\(135+183)r=(183-135)v\\\\318r=48v\\\\\text{ *** We divide by 48 both sides ***}\\\\\boxed{v = \dfrac{318}{48} \cdot r= \dfrac{159}{24} \cdot r}[/tex]

But we can as well use the second equation:

[tex]3(v+r)=183\\\\v+r=\dfrac{183}{3}=61\\\\\dfrac{159}{24}r+r=61\\\\\dfrac{159+24}{24}r=61\\\\\boxed{r = \dfrac{61*24}{183}=8}[/tex]

and then

[tex]\boxed{v=\dfrac{159*8}{24}=53}[/tex]

Hope this helps.

Do not hesitate if you need further explanation.

Thank you

Answer:

Step-by-step explanation:

3(2)^2 + 4(1)^2

3(4) + 4

12+4= 16

Answer:

[tex]\huge\boxed{16}[/tex]

Step-by-step explanation:

[tex]3x^2+4y^2\ \text{for}\ x=2;\ y=1.\\\\\text{Substitute:}\\\\3(2)^2+4(1)^2=3(4)+4(1)=12+4=16\\\\\text{Used PEMDAS}[/tex]

Answer:

1584$

Step-by-step explanation:

Original price is 1800$ (100%)

Discount percent: 12%

=> The price after discount is 100 - 12 = 88% of original price

=> The price after discount is 1800 x 88% = 1800 x 88/100 = 1584$

Answer:

13200

Step-by-step explanation:

12% - 1800

100% - x

X = (1800x100)/12 = 15000 - original price

15000-1800 = original price - discount = 13200 price after discount

Answer: 0.0548

Step-by-step explanation:

Given, A research study investigated differences between male and female students. Based on the study results, we can assume the population mean and standard deviation for the GPA of male students are µ = 3.5 and σ = 0.05.

Let [tex]\overline{X}[/tex] represents the sample mean GPA for each student.

Then, the probability that the random sample of 100 male students has a mean GPA greater than 3.42:

[tex]P(\overline{X}>3.42)=P(\dfrac{\overline{X}-\mu}{\dfrac{\sigma}{\sqrt{n}}}>\dfrac{3.42-3.5}{\dfrac{0.5}{\sqrt{100}}})\\\\=P(Z>\dfrac{-0.08}{\dfrac{0.5}{10}})\ \ \ [Z=\dfrac{\overline{X}-\mu}{\dfrac{\sigma}{\sqrt{n}}}]\\\\=P(Z>1.6)\\\\=1-P(Z<1.6)\\\\=1-0.9452=0.0548[/tex]

hence, the required probability is 0.0548.

Answer:

3

Step-by-step explanation:

3

You did not give any options but i will try to answer.

y < -lxl basically means that the value of y is less than the absolute value of x time - 1.

So if x = 2, then y is any number less than -2.

And if x is -3. then y is any number less than -3.

Happy to help!

This question is not complete. This is because it lacks the appropriate diagram containing necessary information to solve this question.

Please find attached the appropriate diagram to solve for this question

Complete Question :

The surface area of a given cone is 1,885.7143 square inches. What is the slant height?

Answer:

25 inches

Step-by-step explanation:

In the diagram, we are given the following information

Height of the cone = 20 inches

Radius of the cone = 15 inches.

The formula for the slant height of a cone represented by l =

l² = r² + h²

l = √(r² + h²)

l = √(15² + 20²)

l = √(225 + 400)

l = √625

l = 25 inches

Therefore, the slant height of this cone = 25 inches

Answer:

[tex] E(X) =\int_{4}^7 \frac{1}{3} x[/tex]

[tex] E(X) = \frac{1}{6} (7^2 -4^2) = 5.5[/tex]

Now we can find the second moment with this formula:

[tex] E(X^2) =\int_{4}^7 \frac{1}{3} x^2[/tex]

[tex] E(X^2) = \frac{1}{9} (7^3 -4^3) = 31[/tex]

And the variance for this case would be:

[tex] Var(X)= E(X^2) -[E(X)]^2 = 31 -(5.5)^2 = 0.75[/tex]

And the standard deviation is:

[tex] Sd(X)= \sqrt{0.75}= 0.866[/tex]

Step-by-step explanation:

For this case we have the following probability density function

[tex] f(x)= \frac{1}{3}, 4 \leq x \leq 7[/tex]

And for this case we can find the expected value with this formula:

[tex] E(X) =\int_{4}^7 \frac{1}{3} x[/tex]

[tex] E(X) = \frac{1}{6} (7^2 -4^2) = 5.5[/tex]

Now we can find the second moment with this formula:

[tex] E(X^2) =\int_{4}^7 \frac{1}{3} x^2[/tex]

[tex] E(X^2) = \frac{1}{9} (7^3 -4^3) = 31[/tex]

And the variance for this case would be:

[tex] Var(X)= E(X^2) -[E(X)]^2 = 31 -(5.5)^2 = 0.75[/tex]

And the standard deviation is:

[tex] Sd(X)= \sqrt{0.75}= 0.866[/tex]

Answer:

A) 0.99413

B) 0.00022

Step-by-step explanation:

A) First of all let's find the total grading time from 6:50 P.M to 11:00 P.M.:

Total grading time; X = 11:00 - 6:50 = 4hours 10minutes = 250 minutes

Now since we are given an expected value of 5 minutes, the mean grading time for the whole population would be:

μ = n*μ_s ample = 42 × 5 = 210 minutes

While the standard deviation for the population would be:

σ = √nσ_sample = √(42 × 6) = 15.8745 minutes

To find the z-score, we will use the formula;

z = (x - μ)/σ

Thus;

z = (250 - 210)/15.8745

z = 2.52

From the z-distribution table attached, we have;

P(Z < 2.52) ≈ 0.99413

B) solving this is almost the same as in A above, the only difference is an additional 10 minutes to the time.

Thus, total time is now 250 + 10 = 260 minutes

Similar to the z-formula in A above, we have;

z = (260 - 210)/15.8745

z = 3.15

P(Z > 3.15) = 0.00022

Answer:

-1.031 m/s or  [tex]\frac{-\sqrt{17} }{4}[/tex]

Step-by-step explanation:

We take the length of the rope from the dock to the bow of the boat as y.

We take x be the horizontal  distance from the dock to the boat.

We know that the rate of change of the rope length is [tex]\frac{dy}{dt}[/tex] = -1 m/s

We need to find the rate of change of the horizontal  distance from the dock to the boat =  [tex]\frac{dx}{dt}[/tex] = ?

for x = 4

Applying Pythagorean Theorem we have

[tex]1^{2} +x^{2} =y^{2}[/tex]    .... equ 1

solving, where x = 4, we have

[tex]1^{2} +4^{2} =y^{2}[/tex]

[tex]y^{2} = 17[/tex]

[tex]y = \sqrt{17}[/tex]

Differentiating equ 1 implicitly with respect to t, we have

[tex]2x\frac{dx}{dt} = 2y\frac{dy}{dt}[/tex]

substituting values of

x = 4

y = [tex]\sqrt{17}[/tex]

[tex]\frac{dy}{dt}[/tex] = -1

into the equation, we get

[tex]2(4)\frac{dx}{dt} = 2(\sqrt{17} )(-1)[/tex]

[tex]\frac{dx}{dt} = \frac{-\sqrt{17} }{4}[/tex] = -1.031 m/s

The answer is 86.4 km

Explanation:

The graph shows the gift shop is to the east of the science lab, and, between the gift shop and the science lab it is the art supply. Besides this, the description of the graph provides the distance between the art supply and the science lab, which is 40.0, as well as, the distance between the art supply and the gift shop, which is 46.4 kilometers.

In this context, it is possible to calculate the distance from the science lab to the gift shop by adding the partial distances, considering the art supply as a middle point in the map. This means the distance from the lab to the gift shop = 40.0 km (distance from the lab to the art supply) + 46.4 km (distance from the art supply to the gift shop) = 86.4 km.

Question:

Vector A has x and y components of −8.80 cm  and 18.0 cm , respectively; vector B has x and  y components of 12.2 cm and −6.80 cm , respectively.  If A − B +3 C = 0, what are the components of C?

Answer:

x = ___ cm

y = ___ cm

Answer:

x = 7.0cm

y = -8.27cm

Step-by-step explanation:

For a vector F, with x and y components of a and b respectively, its unit vector representation is as follows;

F = ai + bj              [Where i and j are unit vectors in the x and y directions respectively]

Using this analogy, let's represent vectors A and B from the question in their unit vector notation.

A has an x-component of -8.80cm and y-component of 18.0cm

B has an x-component of 12.2cm and y-component of -6.80cm,

In unit vector notation, these become;

A = -8.80i + 18.0j

B = 12.2 i + (-6.80)j = 12.2i - 6.80j

Also, there is a third vector C. Let the x and y components of C be a and b respectively. Therefore,

C = ai + bj

Now,

A - B + 3C = 0                [substitute the vectors]

=> [-8.80i + 18.0j] - [12.2 i -6.80j] + [3(ai + bj)] =  0        [open brackets]

=> -8.80i + 18.0j - 12.2 i + 6.80j + 3(ai + bj) =  0

=> -8.80i + 18.0j - 12.2 i + 6.80j + 3ai + 3bj =  0

=> -8.80i + 18.0j - 12.2 i + 6.80j + 3ai + 3bj =  0  [collect like terms and solve]

=> -8.80i  - 12.2 i  + 3ai + 6.80j + 18.0j + 3bj =  0

=> -21.0 i  + 3ai + 24.8j + 3bj =  0       [re-arrange]

=> 3ai + 3bj = 21.0i - 24.8j

Comparing both sides shows that;

3a = 21.0  -------------(i)

3b = -24.8    -----------(ii)

From equation (i)

3a = 21.0

a = 21.0 / 3 = 7.0

From equation (ii)

3b = -24.8

b = -24.8 / 3

b = -8.27

Therefore, the x-component and y-component of vector B which are a and b, are 7.0cm and -8.27cm respectively.

Answer:

y-intercept is (0,-10) and x-intercept is (-6,0).  Connect them by a straight line to graph the given equation.

Step-by-step explanation:

The given equation of line is

[tex]3y=-5x-30[/tex]

For x=0,

[tex]3y=-5(0)-30[/tex]

[tex]3y=-30[/tex]

[tex]y=-10[/tex]

So, y-intercept is at point (0,-10).

For y=0,

[tex]3(0)=-5x-30[/tex]

[tex]0=-5x-30[/tex]

[tex]5x=-30[/tex]

[tex]x=-6[/tex]

So, x-intercept is at point (-6,0).

Now, plot the point (0,-10) and (-6,0) on a coordinate plane and connect them by a straight line to graph the given line as shown below.

Answer:b

Step-by-step explanation:

Answer:

3.27 hours

Step-by-step explanation:

Calculate the difference in speed and distance between the trains.

The relative speed:

101 - 90 = 11 mph

Difference in distance:

42 - 6 = 36 miles

[tex]time=\frac{distance}{speed}[/tex]

[tex]t=\frac{36}{11}[/tex]

[tex]t = 3.27[/tex]

Answer:

The probability that at least 4 of them use their smartphones is 0.1773.

Step-by-step explanation:

We are given that when adults with smartphones are randomly selected 15% use them in meetings or classes.

Also, 15 adult smartphones are randomly selected.

Let X = Number of adults who use their smartphones

The above situation can be represented through the binomial distribution;

[tex]P(X = r) = \binom{n}{r}\times p^{r} \times (1-p)^{n-r} ; n = 0,1,2,3,.......[/tex]

where, n = number of trials (samples) taken = 15 adult smartphones

           r = number of success = at least 4

           p = probability of success which in our question is the % of adults

                 who use them in meetings or classes, i.e. 15%.

So, X ~ Binom(n = 15, p = 0.15)

Now, the probability that at least 4 of them use their smartphones is given by = P(X [tex]\geq[/tex] 4)

P(X [tex]\geq[/tex] 4) = 1 - P(X = 0) - P(X = 1) - P(X = 2) - P(X = 3)

= [tex]1- \binom{15}{0}\times 0.15^{0} \times (1-0.15)^{15-0}-\binom{15}{1}\times 0.15^{1} \times (1-0.15)^{15-1}-\binom{15}{2}\times 0.15^{2} \times (1-0.15)^{15-2}-\binom{15}{3}\times 0.15^{3} \times (1-0.15)^{15-3}[/tex]

= [tex]1- (1\times 1\times 0.85^{15})-(15\times 0.15^{1} \times 0.85^{14})-(105 \times 0.15^{2} \times 0.85^{13})-(455 \times 0.15^{3} \times 0.85^{12})[/tex]

= 0.1773