According to a recent survey by the National Retail Federation, men spent an average of $135.35 on Valentine's Day gifts.  Assume the standard deviation for this population is $40 and that it is normally distributed.  A random sample of 10 men who celebrate Valentine's Day was selected. a. What is the probability that the sample mean will be between $120 and $160?             b. Identify the symmetrical interval that includes 95% of the sample means if the true population mean is $135.35.

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.4: Distributions Of Data
Problem 19PFA
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According to a recent survey by the National Retail Federation, men spent an average of $135.35 on Valentine's Day gifts.  Assume the standard deviation for this population is $40 and that it is normally distributed.  A random sample of 10 men who celebrate Valentine's Day was selected.

a. What is the probability that the sample mean will be between $120 and $160?            

b. Identify the symmetrical interval that includes 95% of the sample means if the true population mean is $135.35. 

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