Suppose random samples were selected independently from the ???? and ???? populations with ???????? = 15 and ???????? = 18, and suppose further, the normality assumptions of the two-sample ????-test do not appear to be valid. Use the information in Table 7.43 for the bootstrap sampling distribution of ????̄ −????̄ to answer the following questions.

(a) Based on the information in Table 7.42, what is the approximate standard error of ????̄ − ????̄?

(b) Based on the information in Table 7.42, is there sufficient statistical evidence to conclude ???????? ≠ ????????? Explain.