In order to set​ rates, an insurance company is trying to estimate the number of sick days that full time workers at an auto repair shop take per year. A previous study indicated that the population standard deviation is 2.8 days. How large a sample must be selected if the company wants to be​ 95% confident that the true mean differs from the sample mean by no more than 1​ day?
A. 512
B. 1024
C. 141
D. 31

Answers

Answer 1

Answer:

D. 31

Step-by-step explanation:

We have that to find our [tex]\alpha[/tex] level, that is the subtraction of 1 by the confidence interval divided by 2. So:

[tex]\alpha = \frac{1 - 0.95}{2} = 0.025[/tex]

Now, we have to find z in the Ztable as such z has a pvalue of [tex]1 - \alpha[/tex].

That is z with a pvalue of [tex]1 - 0.025 = 0.975[/tex], so Z = 1.96.

Now, find the margin of error M as such

[tex]M = z\frac{\sigma}{\sqrt{n}}[/tex]

In which [tex]\sigma[/tex] is the standard deviation of the population and n is the size of the sample.

A previous study indicated that the population standard deviation is 2.8 days.

This means that [tex]\sigma = 2.8[/tex]

How large a sample must be selected if the company wants to be​ 95% confident that the true mean differs from the sample mean by no more than 1​ day?

This is n for which M = 1. So

[tex]M = z\frac{\sigma}{\sqrt{n}}[/tex]

[tex]1 = 1.96\frac{2.8}{\sqrt{n}}[/tex]

[tex]\sqrt{n} = 1.96*2.8[/tex]

[tex](\sqrt{n})^2 = (1.96*2.8)^2[/tex]

[tex]n = 30.12[/tex]

Rounding up, at least 31 people are needed, and the correct answer is given by option D.


Related Questions

What is the perimeter of this shape? Use numbers only. *

Answers

Answer:

13 m.

Step-by-step explanation:

Formula for perimeter of a rectangle: side + side + side + side.

In other words, add every side of the rectangle.

[tex]2.5+4+2.5+4=13.[/tex]

Therefore, 13 meters is the perimeter of this shape.

Answer:

13m

Step-by-step explanation:

Perimeter of a Rectangle: 2(L + W) where L is the Length, and W is the Width of the rectangle.

=> 2(4 + 2.5)

=> 2(6.5)

=> 13

Perimeter of the Figure = 13 m

Hope this helps!

ia had 50 carrot sticks for her
study group to snack on. There were
6 people eating the carrot sticks, and
each person ate an equal number of
carrots until there weren’t enough
left to share equally. How many
carrot sticks were left over? Explain.

Answers

Answer:

8.333333333 or 25 /3​

Step-by-step explanation:

Helllpppp pls answer both questions !!!! 30pts

Answers

A) I believe is 14 but I don’t really understand the question

.Please help with question 21

Answers

Answer:

y=500x+20000

Step-by-step explanation:

2.- Un campesino guarda un doceavo de su trigo cosechado para semilla, un sexto de la misma
cosecha lo convierte en harina y vende 288 kilos. ¿Cuántos kilogramos de trigo cosechó?

Answers

please translate in english

Please no troll include work

Answers

1) 3/4
2) 40/4 = 10/1 = 10
3) 7/10
4) 48/3 = 16/1 = 16
5) 8/9
6) 32/5

if you have any questions, let me know!

f(x) = 2x3 – 3x2 + 5
g(x) = 3x3 + 2x2 – 4x – 9
Find (f - g)(x).

Answers

Answer This is (3x-23)(23)

The amount of time required to reach a customer service representative has a huge impact on customer satisfaction. Below is the Excel output from a study to see whether there is evidence of a difference in the mean amounts of time required to reach a customer service representative between two hotels. Assume that the population variances in the amount of time for the two hotels are not equal. What is the smallest level of significance at which the null hypothesis will still not be rejected

Answers

Answer:

The smallest level of significance at which the null hypothesis will still not be rejected is 0.05.

Step-by-step explanation:

The [tex]p-[/tex] value of t-test is [tex]0.725009[/tex]. This [tex]p-[/tex] value is greater than [tex]0.05[/tex].

Hence, the null hypothesis is not rejected and conclude that there is no sufficient evidence of a difference in the mean amount of time required to reach a customer service representation between two hotels.

The complete question is :

A child pool is 3.8 feet wide 5.5 feet long and 1.2 fee deep, what is the volume of the pool?

Answers

Answer:

25.08

Step-by-step explanation:

Answer:

25.08 cubic feet

Step-by-step explanation:

v = l * w * h

v = 5.5 * 3.8 * 1.2

v = 25.08 cubic feet

Ling's elementary school principal wants to hire some new teachers. 6 teachers applied for one 1st grade teaching job, and 3 teachers applied for one 2nd grade teaching job. There is also a job opening for a 3rd grade teacher, and 3 teachers applied for the job. How many different ways can Ling's principal hire new teachers?​

Answers

Answer:

Ling's principal can hire new teachers in 54 different ways.

Step-by-step explanation:

Since Ling's elementary school principal wants to hire some new teachers, and 6 teachers applied for one 1st grade teaching job, and 3 teachers applied for one 2nd grade teaching job, and there is also a job opening for a 3rd grade teacher, and 3 teachers applied for the job, to determine how many different ways can Ling's principal hire new teachers the following calculation has to be done:

6 x 3 x 3 = X

18 x 3 = X

54 = X

Therefore, Ling's principal can hire new teachers in 54 different ways.

Is the expression 3x+2 a binomial?

Answers

Yes, this is a polynomial, but a special form of a polynomial with just one term which is called a monomial .

does anyone know what happened to the tutors??

Answers

Answer:

Hey! I'm honestly not sure.

Step-by-step explanation:

I dont have the app... but on the website I'm pretty sure they dont have any.

Have a nice day <3

Which sentence has the quotation marks placed correctly ?

1.) “Mother ," I cut my finger , said Jane.

2.) "Mother, I cut my finger," said Jane.

3.) Mother, I cut my finger, "said Jane."

4.) "Mother, I cut my finger, said Jane."

Answers

“Mother”, I cut my finger, said Jane.
Option 2 is correct.

dele took 25 minutes to walk to school and he arrived at exactly 8:00am, at what time did he leave his home​

Answers

i think it would be around 7:30am

A lawn service owner is testing new weed killers. He discovered that a particular weed killer was effective 89% of time. Suppose that this estimate was based on a random sample of 60 applications. Find the lower confidence limit (LCL) for a 90% confidence interval for p, the true proportion of weeds killed by this particular brand. Round your answer to two decimal places.

Answers

Answer:

The LCL for a 90% confidence interval for p is 0.82.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of [tex]\pi[/tex], and a confidence level of [tex]1-\alpha[/tex], we have the following confidence interval of proportions.

[tex]\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]

In which

z is the zscore that has a pvalue of [tex]1 - \frac{\alpha}{2}[/tex].

A lawn service owner is testing new weed killers. He discovered that a particular weed killer was effective 89% of time. Suppose that this estimate was based on a random sample of 60 applications.

This means that [tex]\pi = 0.89, n = 60[/tex]

90% confidence level

So [tex]\alpha = 0.1[/tex], z is the value of Z that has a pvalue of [tex]1 - \frac{0.1}{2} = 0.95[/tex], so [tex]Z = 1.645[/tex].

The lower limit of this interval is:

[tex]\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.89 - 1.645\sqrt{\frac{0.89*0.11}{60}} = 0.8236[/tex]

Rounding to two decimal places, the LCL for a 90% confidence interval for p is 0.82.

Can someone please help me I will mark u brilliant

Answers

Answer:

11

Step-by-step explanation:

just count all the Xs from 4 and up

large pies cost $5 and small pots cost $2. If $45 pies were sold for $120 how many small pies were sold​

Answers

Answer:

I'm assuming that's supposed to just be 45, not $45

Step-by-step explanation:

35 small pies were sold

10 large pies = $50

35 small pies = $70

50 + 70 = 120

if A(2;2) and B(-3;4), determine the equation of AB, in the form y=mx+c​

Answers

Answer:

[tex]y = -\frac{2}{5}x + \frac{14}{5}[/tex]

Step-by-step explanation:

Equation of a line:

The equation of a line has the following format:

[tex]y = mx + c[/tex]

In which m is the slope and c is the y-intercept(value of y when x = 0).

A(2;2) and B(-3;4)

When we have two points, the slope is the change in y divided by the change in x. So

Change in y: 4 - 2 = 2

Change in x: -3 - 2 = -5

Slope: [tex]m = \frac{2}{-5} = -\frac{2}{5}[/tex]

So

[tex]y = -\frac{2}{5}x + c[/tex]

A(2;2)

When [tex]x = 2, y = 2[/tex]. We use this to find c.

[tex]y = -\frac{2}{5}x + c[/tex]

[tex]2 = -\frac{2}{5}(2) + c[/tex]

[tex]c = 2 + \frac{4}{5} = \frac{10}{5} + \frac{4}{5} = \frac{14}{5}[/tex]

So

[tex]y = -\frac{2}{5}x + \frac{14}{5}[/tex]

What are the zeros of the function f(x) = (x + 5)(2x-3)?
O A. x=-5 and x = 8
O B. x = -5 and x = 4
O C. x = 5 and x = -8
O D. x = 5 and x = -4

Answers

The answer would be C done this yesterday

What is the surface area?
4 ft
4 ft
4 ft

Answers

The surface area of what shape exactly?

Answer:

Hello! answer: 96

Step-by-step explanation:

I'm assumung this is a cube sense cubes will equal the same for all 6 sides we just have to find 1 side then just multiply by 6 to get the answer easy peasy!!! so 4 × 4 = 16 and 16 × 6 = 96 so 96 is our surface area Hope that helps!

Find the volume of this triangular prism.
Be sure to include the correct unit in your answer.

Answers

Answer:

243 ft^3

Step-by-step explanation:

The volume of a triangular prism is the triangular base times the height.

To get the area of the triangle, multiply the base time height and divide by 2.

9*6/2=27

Now multiply by the height

27*9=243

Answer: 243 ft^3

Answer:

243ft^3

Step-by-step explanation:

2x+y=3
x-y= 1

solve the equation ​

Answers

Answer:

x = 4/3

y = 1/3

Step-by-step explanation:

System of equations! This is set up really well to make the second equation equal x then substitute.

x - y = 1

x = 1 + y

and then our substitution:

2 (1+y) + y = 3

and solve:

2 + 2y + y = 3

3y + 2 = 3

3y = 1

y = 1/3

And now we can substitute that value into one of our equations:

x - (1/3) = 1

x = 4/3

Next we should check by substituting these values into both of our equations:

2 (4/3) + (1/3) = 3

9 / 3 does equal 3 !

(4/3) - (1/3) does equal 1 !

Therefore, x = 4/3 , and y = 1/3

Answer: x = 4/3, y = 1/3

Explanation:

2x + y = 3
x - y = 1
=> x = 1 + y

2(1 + y) + y = 3
2 + 2y + y = 3
3y = 3-2
y = 1/3

x - 1/3 = 1
x = 3/3 + 1/3
x = 4/3

A student's four test scores were 88, 91, 93 and 86. What score would be needed on a fifth test to obtain a mean of 90 for all five test?
A. 90
B. 92
C. 95
D. 96

Answers

Answer:

92

Step-by-step explanation:

88 + 91 + 93 + 86 = 358

90*5 = 450

therefore the fifth test has to be 450 - 358 = 92

Sally has 3 yards of yarn. She will use 6 inches per bracelet. How many bracelets can she make?

Answers

3 feet in a yard... 12x3 = 36...... 36+36+36 =108 inches

108 divided by 6 is 18 bracelets

A motorboat travels 102 miles in 3 hours going upstream. It travels 186 miles going downstream in the same amount of
time. What is the rate of the boat in still water and what is the rate of the current?

Rate of the boat in still water:

Rate of the current:

Answers

Answer:

Rate in still water = 48 mph.

Rate of current = 14 mph.

Step-by-step explanation:

Let the rate in still water be x and rate of the current be y miles per hour.

Upstream:

x - y = 102/3

Downstream:

x + y = 186/3

Adding the 2 equations

2x = 102/3 + 186/3 = 34 + 62

2x = 96

x = 48 mph.

So 48 - y = 34

y = 48 - 34 = 14 mph.

Chapter 6 Introduction to Variables and Evaluating Expression
Mathematics, Algebra 1
Question 1
Simplify: -2s - 9+7 - 5r use s = 3 and r= -8

Answers

I would say the answer is -62. Hope this helps

the hypotenuse of a 30-60-90 degree right triangle has a measure of 10. what is the measure of the shortest side

Answers

Answer:

5

Step-by-step explanation:

A 30-60-90 triangle's sides equal as follows:

Hypotanuse= x (a number)

Long side= x/2( also can be calculated as x* 1/2) * [tex]\sqrt{3}[/tex]

Short side = x/2 or x * 1/2

83. A student estimated the height of a tree as 47
feet. If the actual height is 53 feet, what is the
percent error rounded to the nearest percent?
(Hint: Compare the estimated height to the actual
height.)
Poviow (SARZA
Page 8

Answers

I believe it’s 89%. I divided the estimated height by the actual height (47/53=0.8867) and then turned it into a percentage (0.8867=89%)

Can someone help me please?

Answers

9515 1404 393

Answer:

  10 inches

Step-by-step explanation:

Use the formula for the area of a trapezoid. Fill in the given information and solve for the unknown.

  A = 1/2(b1 +b2)h

  50 in² = (1/2)(3 in +7 in)h

  50 in²/(5 in) = h . . . . . . . . . . divide by the coefficient of h

  10 in = h

The height of the trapezoid is 10 inches.

Help please this is for an important test

A cup on the teacher's desk contains 12 pens. There are 3 pens with blue ink and 9 pens with black ink. One student at a time selects a pen at random to sign the attendance sheet and then puts the pen back in the cup.

What is the probability that the first three students all randomly select a pen with blue ink?

A. 1/4
B. 1/27
C. 1/64
D. 1/220

Answers

We have 12 pens in total

P(first three pens are blue with replacement) = 3/12 * 3/12 * 3/12 =

(1/4) * (1/4) * (1/4) =

1/ 64

The required probability  that the first three students all randomly select a pen with blue ink is 1/64. option C is correct.

Given that,
A cup on the teacher's desk contains 12 pens. There are 3 pens with blue ink and 9 pens with black ink. One student at a time selects a pen at random to sign the attendance sheet and then puts the pen back in the cup.

What is probability?

Probability can be defined as the ratio of favorable outcomes to the total number of events.

Here,
Total number of sample = 12
Favorable outcome = 3
Required probability  that the first three students all randomly select a pen with blue ink = 3 / 12 × 3 / 12 × 3 / 12
                             = 1 / 64

Thus, the required probability  that the first three students all randomly select a pen with blue ink is 1/64. option C is correct.

Learn more about probability here:

brainly.com/question/14290572

#SPJ5


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