Earnings of mexican street vendors. refer to the world development (february 1998) study of street vendors in the city of puebla, mexico, exercise 4.6 (p. 184). recall that the vendors’ mean annual earnings, e(y), was modeled as a first-order function of age (x1) and hours worked (x2). now, consider the interaction model e(y) = β0 + β1x1 + β2x2 + β3x1x2. the sas printout for the model is displayed in the next column. (a) give the least squares prediction equation. (b) what is the estimated slope relating annual earnings (y) to age (x1) when number of hours worked (x2) is 10? interpret the result. (c) what is the estimated slope relating annual earnings (y) to hours worked (x2) when age (x1) is 40? interpret the result.

Alarge university wanted to study the relationship between completing an internship during college and students' future earning potential. prom the same graduating class, they selected a random sample of 80 students who completed an internship and 100 students who did not complete an internship and examined their salaries five years after graduation. they found that there was a statistically higher mean salary for the internship group than for the noninternship group. which of the following interpretations is the most appropriate? a. there could be a confounding variable, such as student major, that explains the difference in mean salary between the internship and no internship groups.b. we cannot infer anything from these data since the distribution of salaries is likely right skewed.c. you cannot draw any valid conclusions because the sample sizes are different.d. more students should complete internships because having an internship produces a higher salary.