Suppose That You Want to Perform a Hypothesis Test Based

Suppose that you want to perform a hypothesis test based on independent simple random samples to compare the means of two populations. Several procedures are available, namely, the pooled t-test, the nonpooled t-test, and the Mann-Whitney test. Give circumstances for which the Mann-Whitney test would be the most appropriate procedure. Be sure to comment on the sizes of the samples, the distributions of the variable under consideration on the populations, and the relative shapes of the distributions.