Answer:
(a)
TC(q) [before expansion] = Fixed Cost + Variable Cost
= 750,000 + 1.25q
TC(q) [after expansion] = (750,000 + 350,000) + 0.75q
= 1,100,000 + 0.75q
(b) (i) q = 600,000
TC(q) [before expansion] = 750,000 + (1.25 × 600,000)
= 750,000 + 750,000
= 1,500,000
TC(q) [after expansion] = 1,100,000 + (0.75 × 600,000)
= 1,100,000 + 450,000
= 1,550,000
Since expansion will increase total cost, profit will fall ceteris paribus. So firm should not expand.
(ii) q = 800,000
TC(q) [before expansion] = 750,000 + 1.25 × 800,000
= 750,000 + 1,000,000
= 1,750,000
TC(q) [after expansion] = 1,100,000 + (0.75 × 800,000)
= 1,100,000 + 600,000
= 1,700,000
Since expansion will decrease total cost, profit will rise ceteris paribus. So firm should expand.