If the population mean is expected to be 85 and the sample mean is 80,the sample standard deviation is 20,and the sample consists of 100 consumers,the observed value of the Z-statistic is approximately:
A)2.50
B)-10.00
C)-2.50
D)-0.25

Question

Quizplus · Accepted Answer

The formula for calculating the Z-statistic is:
Z = (sample mean - population mean) / (sample standard deviation / sqrt(sample size))

Plugging in the provided values:
Z = (80 - 85) / (20 / sqrt(100))
Z = -5 / 2
Z = -2.50

Therefore, the answer is choice C) -2.50.

If the Population Mean Is Expected to Be 85 and the Sample