A random sample of size 15 taken from a normally distributed population revealed a sample mean of 75 and a sample variance of 25.The upper limit of a 95% confidence interval for the population mean would equal:
A)77.77
B)72.23
C)88.85
D)77.27

Question

Quizplus · Accepted Answer

The upper limit of a 95% confidence interval for the population mean is calculated using the formula: mean + (t-value * standard error). The standard error is the square root of the variance divided by the sample size. For a sample size of 15, the t-value for 95% confidence is approximately 2.145. Thus, the upper limit is 75 + (2.145 * (5/sqrt(15))) = 77.77.

A Random Sample of Size 15 Taken from a Normally