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11. A questionnaire of spending habits was given to a random sample of college students. Each student was asked to record and Report the amount of money they spent on textbooks in a semester. The sample of 130 students resulted in an average of $422 with a standard deviation of 57 dollars. a. give a 90% confidence interval for the mean amount of money spent by college students on textbooks. b. What is the margin of error for 90% confidence interval? c. how many students should you sample if you want the margin of error of $5 for a 90% confidence interval? |

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Related textbook solutions

Introductory Statistics
OER Edition, 2013
Openstax
ISBN: 9781938168208

Related questions

Suppose a random sample of size 10 was taken from a normally distributed population, and the sample standard deviation was calculated to be s = 5.2.

 

a)  Calculate the margin of error for a 95% confidence interval for the population mean.

 

Give your response to at least 3 decimal places.

   

 

 

b)  Calculate the margin of error for a 90% confidence interval for the population mean.

 

Give your response to at least 3 decimal places.

 

. SAT scores are distributed with a mean of 1,500 and a standard deviation of 300. You are interested in estimating the average SAT score of first-year students at your college. If you would like to limit the margin of error of your 95% confidence interval to 25 points, how many students should you sample? Make sure to give a whole number answer

2. We wish to estimate what percent of adult residents in a certain county are parents. Out of 600 adult residents sampled, 354 had kids. Based on this, construct a 95% confidence interval for the proportion, p, of adult residents who are parents in this county.
Give your answers as decimals, to three places.

A simple random sample of 60 items resulted in a sample mean of 80. The population standard deviation is 15 .

a. Compute the 95% confidence interval for the population mean. Round your answers to one decimal place.
( ,  )

b. Assume that the same sample mean was obtained from a sample of 120 items. Provide a 95% confidence interval for the population mean. Round your answers to two decimal places.
( ,  )

c. What is the effect of a larger sample size on the interval estimate?

Larger sample provides a  margin of error.
 

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