Question

The makers of a soft drink want to identify the average age of its consumers. A sample of 25 consumers was taken. The average age in the sample was 32 years with a sample standard deviation of 5 years. Please answer the following questions:

a. Construct a 95% confidence interval estimate for the mean of the consumers’ age.

b. Suppose a sample of 51 was selected (with the same mean and the sample standard deviation). Construct a 95% confidence interval for the mean of the consumers’ age.

Answer 1

32 2.064 ( 5 / 25 )

32   2.064

( 23.936 , 34.064 )

A 95 % CI for population mean is ( 23.936 , 34.064 )

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b )

32 2.009 ( 5 / 51 )

32 1.406

( 30.594 , 33.406 )

A 95 % CI for population mean is( 30.594 , 33.406 )