Question

A can do a certain work in the same time in which B and C together can do it. If A and B together could do it in 10 days and C alone in 50 days, then B alone could do it in:

विकल्प

• 15 days

• 20 days

• 25 days

• 30 days

Answer 1

25 days

Explanation:

(A + B)'s 1 day's work = `1/10`

C’s 1 day's work = `1/50`

(A + B + C)'s 1 day's work = `(1/10 + 1/50) = 6/50 = 3/25`  ......(i)

A’s 1 day's work = (B + C)’s 1 day’s work  ......(ii)

From (i) and (ii), we get: 2 × (A’s 1 day's work) = `3/25`

⇒ A’s 1 day’s work = `3/50`

∴ B’s 1 day's work `(1/10 - 3/50) = 2/50 = 1/25`

So, B alone could do the work in 25 days.