Question

You measure 50 textbooks' weights, and find they have a mean weight of 79 ounces. Assume the population standard deviation is 12.4 ounces. Based on this, construct a 99.5% confidence interval for the true population mean textbook weight. Keep 4 decimal places of accuracy in any calculations you do. Report your answers to four decimal places. Confidence Interval

Answer 1

Solution:

No. Of sample = 50

Sample mean = 79

Population standard deviation = 12.4

Alpha = 0.005

Alpha/2 = 0.0025

Zalpha/2 = 2.81

So 99.5% confidence interval can be calculated as

79+/- 2.81*12.4/Sqrt(50)

79+/-4.9277

So 99.5% confidence interval is

74.0723 to 83.9277