23、The mean and standard deviation of the net incomes for all companies making up a stock index is $3.5 million and $4.2 million, respectively. If a random sample of 49 companies is taken from the index, the standard error of the sample mean is closest to:

A. $71,429.

B. $85,714.

C. $500,000.

D. $600,000.

答案和详解如下：

23、Correct answer is D

"Sampling and Estimation," Richard A. Defusco, Dennis W. McLeavey, Jerald E. Pinto, and David E. Runkel

2008 Modular Level I, Vol. 1, pp. 439-441

Study Session 3-10-e

calculate and interpret the standard error of the sample mean

The standard error of the sample mean is equal to the population standard deviation divided by the square root of the number of companies in the sample. $4,200,000 / 7 = $600,000.