A simple random sample of size 41 has mean $\bar { x } = 70.55$ and standard deviation s = 15.73. The population distribution is unknown. Determine the correct method of finding a 90% confidence Interval for the population mean and compute it.
A) t-method: (66.41, 74.69)
B) z-method: (66.41, 74.69)
C) z-method: (66.51, 74.59)
D) Cannot compute: the population size is too small.

Question

Quizplus · Accepted Answer

Since the population standard deviation is unknown and the sample size is less than 30, the t-distribution should be used to compute the confidence interval.

A Simple Random Sample of Size 41 Has Mean xˉ=70.55\bar { x } = 70.55xˉ=70.55

A Simple Random Sample of Size 41 Has Mean $\bar { x } = 70.55$