Question

Randomly selected statistics students participated in an experiment to test their ability to determine when 1 minute (or 60 seconds) has passed. Forty students yielded a sample mean of 58.3 sec with a standard deviation is 9.5 sec, construct a 95% confidence interval estimate of the population mean of all statistics students.

A. 50.4 sec < mu  < 77.8

B. 54.5 sec < mu  < 63.2

C. 56.3 sec < mu  < 62.5

D. 55.4 sec < mu  < 61.2

Based on the Confidence Interval for time perception above, is it likely that their estimates have a mean that is less than 60 sec?

Answer 1

95% confidence interval for is

- Z * S / sqrt(n) < < + Z * S / sqrt(n)

58.3 - 1.96 * 9.5 / sqrt(40) < < 58.3 + 1.96 * 9.5 / sqrt(40)

55.4 < < 61.2

Since 60 contained in the confidence interval, we do not have sufficient evidence to support the claim that

mean is less than 60 sec.

No.It is not likely that their estimates have a mean that is less than 60 sec