Question

A can do a piece of work in 15 days and B in 20 days . With the help of C, the work gets finished in 5 days.Hoe long will C take to finish the work alone

Answer 1

Answer:

12 days

Step-by-step explanation:

(i)

Given that A can do a piece of work in 15 days.

Amount of work done by A in 1-day = (1/15).

(ii)

Given that B can do a piece of work in 20 days.

Amount of work done by B in 1 -day = (1/20).

(iii)

Work done by (A + B) in 1-day = (1/15) + (1/20)

                                                    = 7/60

Now,

Given that With the help of C, the work gets finished in 5 days.

Work done by (A + B + C) in 1-day = (1/5).   -------- (iv)

Substitute (iii) in (iv), we get

⇒ 7/60 + C = 1/5

⇒ C = (1/5) - (7/60)

⇒ C = 5/60

⇒ C = 1/12.

Therefore, C will finish the work alone in 12 days.

Hope it helps!