The scores of fourth grade students on a mathematics achievement test follow a normal distribution with a mean of 75 and standard deviation of 4.
a) What is the probability that a single student randomly chosen form all those taking the test scores 80 or higher?
b) What is the probability that the sample mean score of 64 randomly selected student is 80 or higher?
c) What is the probability the sample mean score of 64 randomly selected students is between 74 and 76?

Answers

Answer 1

Answer:

The appropriate solution is:

(a) 0.1056

(b) 0

(c) 0.9544

Step-by-step explanation:

The given values are:

Mean,

[tex]\mu = 75[/tex]

Standard deviation,

[tex]\sigma = 4[/tex]

(a)

⇒  [tex]P(x>80)=1-(x<80)[/tex]

                     [tex]=1-P[\frac{x-\mu}{\sigma} <\frac{80-75}{4} ][/tex]

                     [tex]=1-P[\frac{x-\mu}{\sigma} <\frac{5}{4} ][/tex]

                     [tex]=1-P(z<1.25)[/tex]

By using the table, we get

                     [tex]=1-0.8944[/tex]

                     [tex]=0.1056[/tex]

(b)

According to the question, the values are:

[tex]n[/tex] = 64

[tex]\mu_\bar{x}[/tex] = 75

Now,

⇒  [tex]\sigma_\bar{x}[/tex] = [tex]\frac{\sigma}{\sqrt{n} }[/tex]

         = [tex]\frac{4}{\sqrt{64} }[/tex]

         = [tex]\frac{4}{8}[/tex]

         = [tex]0.5[/tex]

⇒  [tex]P(\bar {x} >80 ) = 1 - P(\bar x <80 )[/tex]

                      [tex]=1 - P[\frac{(\bar x-\mu_\bar x)}{\sigma \bar x} < \frac{80-75}{0.5} ][/tex]

                      [tex]=1-P(z<10)[/tex]

By using the table, we get

                      [tex]=1-1[/tex]

                      [tex]=0[/tex]

(c)

As we know,

⇒ [tex]\sigma_\bar x[/tex] = [tex]\frac{\sigma}{\sqrt{n} }[/tex]

        = [tex]\frac{4}{\sqrt{64} }[/tex]

        = [tex]\frac{4}{8}[/tex]

        = [tex]0.5[/tex]

then,

= [tex]P(74< \bar x <76)[/tex]

= [tex]P[\frac{74-75}{0.5} < \frac{\bar x-\mu \bar x}{\sigma \bar x} < \frac{76-75}{0.5} ][/tex]

= [tex]P(-2<z<2)[/tex]

= [tex]P(z<2)-P(z<-2)[/tex]

By using the table, we get

= [tex]0.9772-0.0228[/tex]

= [tex]0.9544[/tex]


Related Questions

KHAN ACADEMY PLEASE HELP

Answers

Answer is A
Step by step exploration
23not=-23

A store buys 14 sweaters for $84 and sells them for $504. How much profit does the store make per sweater?

Answers

Answer:

$30 per sweater is how much profit the store will make

Step-by-step explanation:

The cost of 1 sweater (for the store) is $6.

The store sells the sweater for $36 (504/14).

The store is making $30 per sweater.

Please help im timed on this

Answers

The slope of the line is 1.25 and the value of x is 12.

What is slope of a line?

A line's slope is defined as the ratio of the change in y coordinate to the change in x coordinate. A line's slope provides information on the steepness and direction of the line. the angle at which two straight lines intersect.

Given that:

rise =10

run = 8

The slope is determined by the following formula:

Slope = Rise / Run

[tex]Slope = \frac{10}{8} = 1.25[/tex] .

The slope of a line equation is given by:

[tex]y_2 - y_1 = m (x_2-x_1)[/tex]

Here, m is the slope of the equation.

Substitute the value of [tex]m= \frac{10}{8}, y_2=21 , y1= 6, x_2 =x, x_1= 0[/tex] in the equation.

[tex]21-6 = \frac{10}{8}(x-0)\\ \\15= \frac{10}{8} (x)\\\\(15)(8) = 10x\\\\120=10x\\\\x=12[/tex]

Hence the value of x is 12.

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Answer:

The slope of the line is 1.25 and the value of x is 12.

Step-by-step explanation:

Solve for x

Pls help

Answers

Answer:

because SRC is the outer angle of the triangle STR

=> SRC = STR + TSR

<=> 101 = 4x + 12 + 7x + 12

<=> 101 = 11x + 24

=> 11x = 77

<=> x = 7

Answer:

7

Step-by-step explanation:

➝4x+12+7x+12=101°

➝4x+7x+12+12=101°

➝11x+24=101°

➝11x=101-24

➝11x=77

➝x=77/11

➝x=7

Check
Annie is comparing the cost to ship a package. One shipping
pound a package weighs. Another shipping company charges $5 for
company charges $7 for the first pound and $0.20 for each additional
the first pound and $0.30 for each additional pound.
Part A
Which equation could be used to determine p, the number of
when the costs for the two shipping companies are the same?
7+0.20p = 5 +0.30p
7+20p = 5 + 30p
A7+0.30p=5+0.20p
B0.20+7p = 0.30 + 5p
Part B
Show
pounds,
For how many pounds is the cost of the two shipping companies the
same?

Answers

Part A: The equation could be used to determine p is B0.20+7p = 0.30 + 5p Part B: Two shipping companies is the same for 25 pounds. Company 1 = $7 + (25 - 1) x $0.20 = $11.80 Company 2 = $5 + (25 - 1) x $0.30 = $11.80.

How to find pounds is the cost of the two shipping companies?

The cost of shipping through two different companies will depend on a variety of factors.

These factors may include the weight and size of the package, the distance it needs to travel, the speed of delivery, and any additional services requested.

Additionally, the cost of shipping may also depend on the type of shipping service used (e.g. ground, air, or express).

To find out the cost of shipping through two different companies, it is best to contact each company directly. This can usually be done by phone, email, or through their website.

Each company will be able to provide a quote based on the package’s specifications. It is then possible to compare the cost of the two shipping companies and determine whether or not the cost is the same.

It is important to note that companies may offer discounts or other incentives for shipping with them.

Therefore, it is important to pay attention to any additional fees or discounts that may apply in order to get the best deal.  

Comparing the cost of two different shipping companies can help to ensure that the most cost-effective option is chosen.

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Reagan went to the playground. She played on the swings for 24 minutes and went on the slide for 13 minutes. It was 4:28 P.M. when Reagan left the playground. What time was it when Reagan arrived at the playground?

Answers

Answer:

If she played on the swings for 24 minutes and on the slide for 13, then she was at the playground for 37 minutes.

If she left the playground at 4:28, then you want to subtract 37 minutes from 4:28.

4:28 - :37 = 3:51.

She arrived at the playground at 3:51

Step-by-step explanation:

Hope it helps! =D

Answer:

3:51 p.m.

Step-by-step explanation:

Add the two amounts of time:

24 minutes + 13 minutes = 37 minutes

She was at the park for 37 minutes. She arrived at the park 37 minutes before 4:28 p.m.

Now we subtract 37 minutes from 4:28 p.m.

Remember that 1 hour = 60 minutes, so when you borrow 1 hour to do the subtraction, you add 60 minutes to the minutes of the time of day.

Borrow 1 hour from 4 hours as 60 minutes. You end up with 3 hours. Then add the 60 minutes to the 28 minutes to get 88 minutes.

4:28 p.m. is the same as 3:88 p.m.

     4:28 p.m.                             3:88 p.m.

-     0:37                 ----->         -  0:37

-------------------                       -------------------

                                                  3:51 p.m.

Answer: 3:51 p.m.

Solve for the value of c

Answers

Answer:

The answer is c=15.

Step-by-step explanation:

.......

almost how many cubes of length 5 cm can be contained in a cuboid of length 20cm, breadth 10 cm,and height 5 cm?find it.​

Answers

Answer:

volume of a cube=5³cm³

=125 cm³

volume of the cuboid=20×10×5

=1000 cm³

number of cubes=1000/125

=8 cubes

This recipe makes 2 portions of fajitas.
Carly has 700 g of chicken, 950 g of peppers, 100 g of onion, 35 g of spice mix
and 20 tortillas.
How much more of each ingredient will she need to make 8 portions by
following this recipe?
Recipe: Serves 2
200 g chicken
250 g peppers
30 g onion
10 g spice mix
4 tortillas

Answers

100g of chicken, 50g of peppers, 20g onions, 5g of spice mix and you have enough tortillas

Marathon Race. Carlos, Maura, and Jacob are running a marathon-26 miles. Carlos runs at a rate of 6 miles per hour. Carlos runs at a rate that is 25% slower than Maura's rate. Jacob takes 2 hours and 36 minutes to finish the marathon. Determine and clearly show everyone's speed. Show or explain your
calculations. Clearly show the exact time it takes for each person to finish the race.

Answers

First, let's find Maura's running speed by using the information that Carlos runs at a rate that is 25% slower than Maura's rate. If Carlos runs at a rate of 6 miles per hour, then Maura runs at a rate of 6 * 1.25 = 7.5 miles per hour.

How to calculate time?

Next, let's calculate how long it takes for Carlos to finish the marathon. We know that Carlos runs at a rate of 6 miles per hour and the marathon is 26 miles long. So we can use the formula:

time = distance/rate

time = 26/6

time = 4.33 hours

Now let's find how long it takes for Maura to finish the marathon. We know that Maura runs at a rate of 7.5 miles per hour and the marathon is 26 miles long. So we can use the formula again:

time = 26/7.5

time = 3.47 hours

Finally, let's convert Jacob's time of 2 hours and 36 minutes to hours. We can use the formula:

time = 2 + (36/60)

time = 2 + 0.6

time = 2.6 hours

In conclusion, Carlos takes 4.33 hours, Maura takes 3.47 hours and Jacob takes 2.6 hours to finish the marathon.

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Evaluate p+(n-1) x3 for n=7 and p=9

Answers

is x3 an exponent ? i answered one of ur earlier questions and i assumed x3 was multiplication

9 + (7 - 1)^3
= 9 + (6)^3
= 9 + (216)
= 225

or if it is multiplication...

then the answer is 27

3. A box contains 7 Green balls, 5 Red balls, and 3 Blue balls. A ball is randomly selected and its color is noted. Then it is replaced into the same box A second ball is selected randomly and its color is noted. Find the probability of each of these questions: a Selecting 1 Blue ball and 1 Green ball. b. Selecting 1 Red ball and 1 blue ball​

Answers

Answer:

a. 7/45

b. 1/15

Step-by-step explanation:

15 total balls

a. Selecting 1 Blue ball and 1 Green ball

3/15 * 7/15 = 21/225 = 7/45

b. Selecting 1 Red ball and 1 blue ball​

5/15 * 3/15 = 15/225 = 1/15

You have a pipe where the last 9/16 of an inch is threaded. Due to error, you need to trim of 4/32" off the threaded part. How long will the threaded section be? A. 17/32, Bl 7/8, C. 7/16 D. 15/32

Answers

The length of 9/16 of an inch threaded section of the pipe indicates that the new length of the threaded section after 4/32 of an inch is trimmed off obtained by the difference between the fractions is; C. 7/16 of an inch

What is a fraction?

A fraction is the representation of only a part of a whole of an item in the form of a quotient, consisting of a numerator, being divided by a denominator.

The length of the threaded section of the pipe = 9/16 of an inch

The length of the threaded part trimmed off due to an error = 4/32 of an inch

The new length of the threaded section following the trimming off of 4/32 is therefore;

New length of the threaded section = 9/16 - 4/32

The value of the difference between the fractions is found as follows;

[tex]\dfrac{9}{16} -\dfrac{4}{32} =\dfrac{2 \times 9 - 4}{32} = \dfrac{14}{32}[/tex]

[tex]\dfrac{14}{32}=\dfrac{7}{16}[/tex]

Therefore;

[tex]\dfrac{9}{16} -\dfrac{4}{32} =\dfrac{7}{16}[/tex]

The new length of the threaded section will be 9/16 - 4/32 = 7/16

The correct option that indicates the new length of the threaded section is C. 7/16

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What is the volume of the prism

Answers

Answer:

24 cm^3

Step-by-step explanation:

you do length times width times height.

The radius of a cylinder is 7 in and the height is 24 in.
Find the Lateral Area.
36011
117611
43411
33611

Answers

Lateral Area of a Cylinder=2πrh

= 2 x π x 7 x 24

=336π

Option D

*will give brainlist*
A town has 1.500 households. The number of people per
household is normally distributed with a mean of 3.67 and
a standard deviation of .34.
Approximately, how many
households have between 3.67 and 4.35 people?
0 510 households
o 945 households
a 715 households
o 660 households

Answers

Answer: The question is asking for the number of households that have between 3.67 and 4.35 people, which corresponds to the number of households whose number of people per household falls within one standard deviation of the mean.

A normal distribution is symmetric, so approximately 68% of the data falls within one standard deviation of the mean. So, we can estimate that approximately 68% of the 1,500 households have between 3.67 and 4.35 people.

The calculation is:

1,500 households x 68% = 1,020 households

So, approximately 1,020 households have between 3.67 and 4.35 people.

This is a rough estimate and the actual number may be slightly different, but it can be considered as a good approximation. From the given options, The answer closest to 1,020 is 945 households.

Step-by-step explanation:

In Circle O, mAB = 72. Find m

Answers

Check the picture below.

25.05+36.05 equal the answer

Answers

Answer:

61.1

Step-by-step explanation:

Here, we simply add the two numbers together.

25+36=61

0.5+0.5=1

so, the answer is 61.1

25.05 + 36.05 is rounded to 61.6

Which complex number lies in the shaded triangle in this graph?

Answers

Answer: 1-i

Step-by-step explanation: If your in algebra 2 then this is the answer

Find tan0, where 0 is the angle shown.
Give an exact value, not a decimal approximation.

Answers

The exact value of tan  θ = 15/ 8

What are trigonometric identities?

Trigonometric Identities are defined as the equalities involving trigonometry functions and also one that holds true for all the values of the variables  in the given equation.

The trigonometric functions are;

sinecosinetangentcotangentsecant

From the information given, we have;

tan θ = opposite/ adjacent

To determine the adjacent sent

17² - 15² = x²

x = √64

x = 8

Substitute the value

tan θ = 15/8

Hence, the value is 15/8

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5 books cost 20 work out the cost of 9 books​

Answers

9 books cost 32

Step-by-step explanation:

5 books =20

1 book= 5÷20 = 4

9 books = 4×9 = 32

Answer:

36

Step-by-step explanation:

5books=20

9books=??

9×20=180

180÷5=36

Compute the probability of X successes, using the binomial formula. (a) n = 5, X = 2, p = 0.025 (b) n = 12, X = 6, p = 0.45 (c) n= 6, X = 0,9 = 0.35 (d) n = 45, X = 10, p = 0.25 (e) n = 22, X = 20, p = 0.68​

Answers

Answer:a) 10. have +05 x 2 P= 0.025 p(x - 2) (B) - (-2)-2 (5) 5-2 (0 •025) ( 1 - 0 025) 3 0 • 00 57 9287 n - 2 . x - -6 m-6 b) we have p= 0 45 p(x = 6) = (P)...

Step-by-step explanation:

Select the correct answer from each drop-down menu. Let d(t) be the total number of miles Joanna has cycled, and let t represent the number of hours after stopping for a break during her ride. So, d(4) = 68 . This means that after a 4 hour break , Joanna cycled 68 miles total .

Answers

The numeric value of the function d(t) = 12t + 20 at t = 4 is given as follows:

d(4) = 48.

The interpretation of this numeric value is that after a time of 4 hours, Joanna has cycled 68 miles.

How to interpret the function?

The function for this problem is defined as follows:

d(t) = 12t + 20.

The meaning of each variable is given as follows:

t: time in hours after the break.d(t): distance cycled after t hours.

The numeric value at t = 4 is obtained replacing the lone instance of t in the function by 4, as follows:

d(4) = 12(4) + 20

d(4) = 48 + 20

d(4) = 68 miles.

Meaning that after a time of 4 hours, the distance cycled by Joanna was of 68 miles.

Missing Information

The function for this problem is defined as follows:

d(t) = 12t + 20.

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SAT scores are normally distributed and in the state of Ohio in 2017, the mean was 1149 with a standard deviation of 212. To get accepted into Yale, you need an SAT of 1460 or an ACT of 33. Which is your best option to get admitted to Yale?
Question 5 options:
1.You should take the ACT because it has a higher z-score
2.You should take the SAT because it takes a lower z-score to get in.
3.Each test has the same z-score value, so you can take either one
4.You should take the SAT because it has a higher z-score
5.You should take the ACT because it takes a lower z-score to get in.

Answers

Answer:

The correct option depends on the ACT z-score. If it's higher than 1.47 the best option is the ACT while if it's lower the best option is the SAT.

Step-by-step explanation:

Z-score:

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

In this question:

Whichever test has the higher z-score should be taken.

SAT scores are normally distributed and in the state of Ohio in 2017, the mean was 1149 with a standard deviation of 212. To get accepted into Yale, you need an SAT of 1460.

This means that [tex]X = 1460, \mu = 1149, \sigma = 212[/tex]

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

[tex]Z = \frac{1460 - 1149}{212}[/tex]

[tex]Z = 1.47[/tex]

Z-score for the ACT:

We don't have the mean.

But the correct option depends on the ACT z-score. If it's higher than 1.47 the best option is the ACT while if it's lower the best option is the SAT.

3/4 divided by 3/7 in simplest form

Answers

Answer:

7/

Step-by-step explanation:

3/4 * 7/

3 can be crossed

Leaving 7/

10 pt
Question 5
The radius of a cylinder is 7 in and the height is 24 in.
Find the Surface Area. (hint: Use the answer from the previous question.)
O 117611
0 33611
0 43411
O 36011

Answers

Answer:

C. 434π

Step-by-step explanation:

Given:

Radius (r) = 7 in.

Height (h) = 24 in.

Required:

Surface area of the cylinder

Solution:

S.A = 2πrh + 2πr²

Plug in the values

S.A = 2*π*7*24 + 2*π*7²

S.A = 336π + 98π

S.A = 434π

I need c15 and c16 doing please with working out thank you

Answers

Therefore , the solution to the given problem of circle comes out to be area = 25.1 sq cm and perimeter=12.5 cm.

What is the circle?

Every position in a circle's plane is equally spaced from the centre and is considered to be a closed, double object. A line of reflected symmetry is created as a result of each line traversing the circle. Each angle also has an axis of symmetry that circles its center.

Here,

Given : Diameter = 8

Radius = 8/2 = 4cm

To find the semi circle area

=>semi circle area = πr²

=>  22/7 * 4² *1/2

=>  25.1 sq cm

To find the perimeter of semi circle :

=> 2πr /2

=> πr

=> 22/7*4

=>12.5 cm

Therefore , the solution to the given problem of circle comes out to be area = 25.1 sq cm and perimeter=12.5 cm.

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Dan pays £240 per week in rent.
His landlord decides to decrease the rent by 2.5%.
How much rent does he pay now?

Answers

Answer:

234 pounds

Step-by-step explanation:

100% - 2.5% = 97.5%

(0.975)(240) = 234

234 pounds

Answer:

Dan pays £234 now.

Step-by-step explanation:

240 - 2.5% * 240 = 234

Therefore, he pays £234.

Thenks and mark me brainliest :))))

Identify the domain and range of the following relation.

x y
-2 -4
1 3
0 0
1 4
4 6
-1 -2

Answers

Answer:

domain = - 2, 1, 0, 1, 4, - 1

range = - 4, 3, 0, 4, 6, - 2

Step-by-step explanation:

x is domain

y is range

An 8-pound bag of dog food costs $25.60. A 12-pound bag of dog food costs $36.60. What is the difference in unit prices?

Answers

Aswer:

36.60-25.60= 11

Step-by-step explanation:

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