Instruction 10-2
a Researcher Randomly Sampled 30 Graduates of an MBA

Instruction 10-2
A researcher randomly sampled 30 graduates of an MBA program and recorded data concerning their starting salaries. Of primary interest to the researcher was the effect of gender on starting salaries. The result of the pooled-variance t test of the mean salaries of the females (Population 1) and males (Population 2) in the sample is given below.
$\begin{array}{|l|r|}\hline \text { Hypothesised Difference } & 0 \\\hline \text {Level of Significance } & 0.05 \\\hline \text { Population 1 Sample } &\\\hline \text { Sample Size } & 18 \\\hline \text { Sample Mean } & 48266.7 \\\hline \text { Sample Standard Deviation } & 13577.63 \\\hline \text { Population 2 Sample } &\\\hline \text { Sample Size } & 12 \\\hline \text { Sample Mean } & 55000 \\\hline \text { Sample StandardDeviation } & 11741.29 \\\hline \text { Differencein Sample Means } & -6733.3 \\\hline t \text {-Test Statistic } & -1.40193\\\hline \text {Lower-Tail Test } & \\\hline \text {Lower Critical Value }& -1.70113 \\\hline \text {p-Value }& 0.085962\\\hline \end{array}$
-Referring to Instruction 10-2,the researcher was attempting to show statistically that the female MBA graduates have a significantly lower mean starting salary than the male MBA graduates.What assumptions were necessary to conduct this hypothesis test?

A) The samples were randomly and independently selected.
B) The population variances are approximately equal.
C) Both populations of salaries (male and female) must have approximate normal distributions.
D) All of the above assumptions were necessary.