A’s work efficiency is 2.5 times more than B’s and B’s efficiency is 0.5 times less than C’s. If A can do a piece of work in 20 days, in ho… — Answer & Discussion

A’s work efficiency is 2.5 times more than B’s and B’s efficiency is 0.5 times less than C’s. If A can do a piece of work in 20 days, in how many days approximately will A, B and C complete the same work?

A111/13 days
B120/11 days
C140/13 days
D142/13 days

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Discussion 1

CCommunity02 Jun 2019

A’s 1 day work = 1/20

A’s efficiency = B’s efficiency + 2.5 × B’s efficiency

⇒ A’s efficiency = 3.5 × B’s efficiency

⇒ B’s efficiency = (2/7) × A’s efficiency

⇒ B’s 1 day work = 2/7 × 1/20 = 1/70

B’s efficiency = C’s efficiency – 0.5 × C’s efficiency

⇒ B’s efficiency = 0.5 × C’s efficiency

⇒ C’s efficiency = 2 × B’s efficiency

⇒ C’s 1 day work = 2 × 1/70 = 1/35

Hence,

(A + B + C) ’s 1 day work = 1/20 + 1/70 + 1/35 = 13/140

∴ They will together complete the work in (140/13) days.