Question

A can finish a piece of work in 16days and b in 20days. They work together for 4days and after that a leaves.How long will b take to complete the remaining work?

Answer 1

Work of A in one day = 1/16
Work of B in one day = 1/20
1/16 + 1/20
= 5/80 + 4/80 = 9/80
9/80 x 4 = 9/20
hence b has to complete 9/20 of the work

Answer 2

Here's your answer!!

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A can finish a piece of work in 16 days.

One day work of A ,

$= > \frac{1}{16}$

B can finish a piece of work in 20 days.

One day work of B ,

$= > \frac{1}{20}$

Now,

(A+B)'s together one day work =

$= > \frac{1}{16} + \frac{1}{20}$

$= > \frac{5 + 4}{80}$

$= > \frac{9}{80}$

It is given that ,they worked for 4 days.

So,fraction of work completed =

$= > \frac{9}{80} \times 4$

$= > \frac{9}{20}$

Therefore,

Remain work =

$= > 1 - \frac{9}{20}$

$= > \frac{20 - 9}{20}$

$= > \frac{11}{20}$

Now,A has left and remain work has to be done by B.

So,time taken by B to complete remain work =

$= > \frac{11}{20} \div \frac{1}{20}$

$= > \frac{11}{20} \times \frac{20}{1}$

$= > 11$

Hence,

B can complete the remain work alone in 11 days.

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Hope it helps you!! :)