A and B together can complete a piece of work in 15 days. B and C together can do it in 24 days. If A is twice as good a workman as C, then in how many days can B alone complete the work?
Answer & explanation
Correct answer: option 2
A + B = 15 days,
B + C = 24 days,
⇒ (A + B) - (B + C) = 8 - 5,
⇒ A - C = 3, ..(1)
⇒ Also, given A : C = 2 : 1
Put it in (1.)
⇒ (2 + 1)x = 3
⇒ x = 3,
⇒ Therefore, A = 2(3), C = 1(3)
⇒ A : C = 6 : 3, (Efficiency)
⇒ B + C = 5,
⇒ B + 3 = 5,
⇒ B = 2,
⇒ Time required by B to complete the total work alone = \(\frac{120}{2}\) = 60 days, ..(\(\frac{Work}{Efficiency}\) = Time)