A student budgets $60 weekly for gas and a few quick meals off-campus. Let denote the amount spent for gas and the amount spent for quick meals in a typical week. Assume this student is very...

A student budgets $60 weekly for gas and a few quick meals off-campus. Let

denote the amount spent for gas and

the amount spent for quick meals in a typical week. Assume this student is very disciplined and sticks to the budget, spending $60 on these two things each week.

(a) Can we model

and

as independent random variables? Explain.

(b) Suppose we assume

and

are dependent. What is the effect of this dependence on the variance of
?