A is 50% as efficient as B. C does half of the work done by A and B together in the same time. If C alone does the work in 20 days, then A, B and C together can do the same work in:
Answer & explanation
Correct answer: option 2
ATQ, C's efficiency is half of the efficiency of (A + B)
Therefore,
A : B : C
Efficiency : 1 : 2 : 3 × \(\frac{1}{2}\)
2 : 4 : 3
Now,
C : A + B + C
Efficiency : 3 : 9
Time : 9 : 3
3 : 1
C does the work in 20 days
⇒ 3R = 20
Time takn by (A + B + C) = 1R = \(\frac{20}{3}\) = 6\(\frac{2}{3}\)