In 2013, the U.S. Census Bureau reported that the population median income was $29,127 for white females,

$26,006 for black females, $41,086 for white males, and

$30,394 for black males.

(a) Identify the response variable and the two factors, and show these medians in a two-way classification of the factors.

(b) Explain why there is interaction in terms of the median.

(c) Show four population median incomes that would satisfy H0: no interaction.