Question

A' and 'b' complete a work togather in 8 days.If 'a' alone can do it in 12 days.Then how many day 'b' will take to complete the work?

Answer 1

Solution :-

A and B complete a work togather in 8 days.

(A + B)'s one day work = 1/8

A alone can do it in 12 days.

A's one work = 1/12

To find : Time taken by B to complete the work alone.

(A + B)'s one day work - A's one day work

= 1/8 - 1/12

= (3 - 2)/24

= 1/24

B's one day work = 1/24

Hence,

B will take 24 days to complete the work.

Answer 2

Answer

Equations formed:

$\tt {\frac {1}{A} + \frac {1}{B} = \frac {1}{8}}$

A can do it in = 12 days

$\tt {\frac {1}{12} + \frac {1}{B} = \frac {1}{8}}$

=> $\tt {\frac {1}{B} = \frac {1}{8} - \frac {1}{12}}$

=> $\tt {\frac {1}{B} = \frac {1}{24}}$

Answer: 24 days