A sample of 12 items yields = 48.5 grams and s = 1.5 grams.Assuming a normal distribution,construct a 90 percent confidence interval for the population mean weight.
A) [47.722,49.278]
B) [47.788,49.212]
C) [45.806,51.194]
D) [47.865,49.135]

Question

Quizplus · Accepted Answer

The correct answer is A because the confidence interval is calculated as x̄ ± z*s/√n, where x̄ is the sample mean, s is the sample standard deviation, n is the sample size, and z is the z-score corresponding to the desired confidence level. For a 90% confidence level, z = 1.645. Plugging in the given values, we get 48.5 ± 1.645*1.5/√12 = [47.722,49.278].

A Sample of 12 Items Yields = 48