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QUESTION 1 A store manager has records of the amounts spent by the most recent s

ID: 2929852 • Letter: Q

Question

QUESTION 1 A store manager has records of the amounts spent by the most recent shoppers. Of the last 100 shoppers, the average amount spent is $18.42. It is known from store records that the standard deviation is $5.27. Calculate the 95% margin of errore, in the mean amount spent by all shoppers. For 95% confidence, use 1.96. Give your answer in dollars correct to the nearest cent (i e. to two decimal places). Do NOT put a dollar sign in your answer. Using the information in the previous question, calculate the sample size required to give 99% confidence if the margin of error is e=$1.30. For 99% confidence, use Z-2.576.

Explanation / Answer

a) Mean = 18.42

SD = 5.27

z = 1.96

e = z *  /n

e = 1.96 * 5.27/100

e = 1.03

b) z at 99% = 2.576

1.3 = 2.576 * 5.27/n

n = 109.06 or 110

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