A and B can do a piece of work in 12 days, B and C in 15 days, C and A in 20…
2017
A and B can do a piece of work in 12 days, B and C in 15 days, C and A in 20 days. How long would A take separately to do the same work?
Answer: B. 30 days 30 दिन — Solution: Find A's time using work rates. Let A, B, C denote the fractions of the work they do per day. From the given: A + B = 1/12, B + C = 1/15, C + A =…
- A.
40 days
40 दिन - B.
30 days
30 दिन - C.
20 days
20 दिन - D.
10 days
10 दिन
Attempted by 7 students.
Show answer & explanation
Correct answer: B
Solution: Find A's time using work rates.
Let A, B, C denote the fractions of the work they do per day.
From the given: A + B = 1/12, B + C = 1/15, C + A = 1/20.
Add the three equations: 2(A + B + C) = 1/12 + 1/15 + 1/20 = 1/5, so A + B + C = 1/10.
Then A = (A + B + C) - (B + C) = 1/10 - 1/15 = 1/30.
So A does the whole work in 30 days.