Answer:
for provider B the surplus is 100
for provider A te surplus is 125
If my friend is a rational consumer it will pick the Provider A
Explanation:
if P = 1 then:
150 - 50(1) = 100
To know the surplus we calculate the area of the demand above the market price:
(P0 -Pm)Qm/2
(3-1) x (100) / 2 = 2 x 100 / 2 = 100
For provider A then P will be zero so
150 - 50(0) = 150 minutes
the surplus will be the area of the demand curve less the fixed cost
3*150/2 - 100 = 225 - 100 = 125