Question

A sample of 105 laramie residents was randomly selected and surveyed about Easter weekend spending. Their...

A sample of 105 laramie residents was randomly selected and surveyed about Easter weekend spending. Their 95% confidence interval for the true average amount of money that Laramie residents spend during the Easter weekend was calculated to be $277< μ < $327. National data shows that the standard deviation of money spent duing easter weekend is $91.00.

a.) What is the error?

b.) If I wanted to calculate a new confidence interval and drop my error to $12.00, how large would my sample size have to be?

Homework Answers

Answer #1

Solution :

  = (Lower confidence interval + Upper confidence interval ) / 2

Sample mean = = (277+327) / 2=302

Margin of error = E = Upper confidence interval -   = 327-302=25

Margin of error = E =25

(B)

Solution

standard deviation =   =$91.00

Margin of error = E = $12.00

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z0.025 = 1.96

sample size = n = [Z/2* / E] 2

n = ( 1.96* 91.00 / 12.00 )2

n =220.9

Sample size = n =221

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
A survey of 100 randomly selected Michigan residents finds that the they spend a mean of...
A survey of 100 randomly selected Michigan residents finds that the they spend a mean of $21 per month on going to the movies. An independent study of a 100 randomly selected California residents find that they spend a mean of $46 per month on going to the movies. Assume that the population standard deviation for the Michigan residents is $5 per month and that the population standard deviation for the California residents is $23 per month. Answer the following...
A mayor of a big city finds that 212 of 400 randomly selected city residents believe...
A mayor of a big city finds that 212 of 400 randomly selected city residents believe that the city should spend more money on road maintenance. Use this information for a large-sample inference of the proportion of all city residents who believe that the city should be spending more. d) (4 points) Based on your findings, is it safe to say that a majority of the city’s population wants more money spent on roads? In other words, can you reject...
Question 3 (1 point) You own a small storefront retail business and are interested in determining...
Question 3 (1 point) You own a small storefront retail business and are interested in determining the average amount of money a typical customer spends per visit to your store. You take a random sample over the course of a month for 42 customers and find that the average dollar amount spent per transaction per customer is $89.687 with a standard deviation of $10.9431. When creating a 99% confidence interval for the true average dollar amount spend per customer, what...
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT