If the population mean is expected to be 550, the sample mean is 525, the sample standard deviation is 20, and the sample consists of 200 consumers, then the observed value of the Z-statistic is approximately:
A) 1.25.
B) 2.5.
C) -1.25.
D) -2.5.

Question

Quizplus · Accepted Answer

The Z-statistic is calculated using the formula Z = (X̄ - μ) / (σ/√n), where X̄ is the sample mean, μ is the population mean, σ is the sample standard deviation, and n is the sample size. Plugging in the given values: Z = (525 - 550) / (20/√200) = -25 / (20/√200) = -25 / (20/14.14) ≈ -1.25.

If the Population Mean Is Expected to Be 550, the Sample