Question

A and B together can do a piece of work in 15 days, while B alone can finish it 20 days. In how many days can A alone finish the work? plzzz. explain with working.

Answer 1

A and B together can do a piece of work in 15 days, while B alone can finish it 20 days. In how many days can A alone finish the work?

Solution:

Time taken by (A + B) to finish the work = 15 days.

(A + B)’s 1 day’s work = 1/15 part

Time taken by B alone to finish the work 20 days.

∴B’s 1 day’s work = 1/20 part

A’s 1 day’s work = {(A + B)’s 1 day’s work} - {B’s 1 day’s work}

= (1/15 - 1/20)

= (4 - 3)/60  [ Lcm of 15 and 20 =60]

= 1/60 part

A alone finish the work in 1/[1/60 part]

=60 days Ans