A random sample of 64 items is selected from a population of 400 items.The sample mean is 200. The population standard deviation is 48.From this data,a 90% confidence interval to estimate the population mean can be computed as _______.
A) 189.21 to 210.79
B) 188.24 to 211.76
C) 190.13 to 209.87
D) 190.94 to 209.06
E) 193.45 to 211.09

Question

Quizplus · Accepted Answer

The 90% confidence interval is calculated using the formula: sample mean ± (Z * (population standard deviation / sqrt(sample size))). With a Z value of 1.645 for 90% confidence, the interval is 200 ± (1.645 * (48 / 8)), which results in 190.94 to 209.06.

A Random Sample of 64 Items Is Selected from a Population