Abigail, Bernard, Cornwallis, and Douglas each derive a distinct amount of utility from consuming apples and bananas. Initially, apples cost $1, bananas cost $2, and each person receives a weekly allowance of $20 to spend. For each of the four sets of preferences described below, calculate the compensating variation if the price of apples rises to $4.
(a) (4) Abigail: U(a,b) = 2a + b
(b) (4) Bernard: U(a,b) = a + 2b
(c) (4) Cornwallis: U(a,b) = a −b
(d) (4) Douglas: U(a,b) = min(a,3b)
