A building construction work can be completed by two masons A and B together in 22.5 days. Mason A alone can complete the construction work in 24 days less than mason B alone. Then mason A alone will complete the construction work in :
- 36 days
- 24 days
- 30 days
- 42 days
Answer
(1) 36 days
Solution
Let A alone take t days B alone takes (t + 24) days.
Work per day together: 1t + 1t + 24 = 122.5 = 245
45(2t + 24) = 2t(t + 24)
t2 - 21t - 540 = 0
(t - 36)(t + 15) = 0
t = 36 days (t > 0)
Answer: (1)