A psychologist is collecting data on the time it takes to learn a certain task. For 50 randomly selected adult subjects, the sample mean is 16.40 minutes and the sample standard deviation is 4.00 minutes. Construct the 95 percent confidence interval for the mean time required by all adults to learn the task.

Confidence interval = (15.29 to 17.51 minutes)

Step-by-step explanation:

the sample mean x = 16.40 minutes

the sample standard deviation r = 4.00 minutes.

Number of samples n = 50

Confidence interval is 95%

Z * = t (0.025) = 1.96

Confidence interval = x + / - (Z * * r/√n)

= 16.40 + / - (1.96 * 4.00/√50)

= 16.40 + / - 1.11

Confidence interval = (15.29 to 17.51 minutes)