A can do a task in 18 days, B can do the same task in 24 days and C can…
2018
A can do a task in 18 days, B can do the same task in 24 days and C can destroy the whole work in 36 days. If A & B work for first x days together after that C also joined them, remaining work is completed in (x + 4 ⁴/₅) days. Find how many days all three worked together?
- A.
6 ⁴/₅ days
- B.
5 ⁴/₅ days
- C.
4 ⁴/₅ days
- D.
7 ⁴/₅ days
- E.
8 ⁴/₅ days
Attempted by 2 students.
Show answer & explanation
Correct answer: E
A and B together work at 1/18 + 1/24 = 7/72 per day. When C joins, net rate = 7/72 - 1/36 = 5/72. If A and B work for x days first and then all three work for x + 4 4/5 days, then 7x/72 + 5(x + 4.8)/72 = 1. This gives x = 4, so all three work for 8 4/5 days.