Question

A, B and C can finish a piece of work in 10, 12 and 15 days respectively. A and B started working then
B left after 2 days. If C joins after 4 days from the start, in how much time, from the moment C joins,
will the remaining work be completed by A and C together?​

Answer 1

Answer:

A, B, C can do 1/10, 1/12, and 1/15 of the work per day respectively.

After 2 days of A, B, C working,

(1/10 + 1/12 + 1/15) * 2

= (6/60 + 5/60 + 4/60) *2

= (15/60) *2

= (1/4)*2

= 1/2 of the work had been done after 2 days.

1/2 of the work has remained.

When A and C work together,

1/10 + 1/15 = (3/30 + 2/30)

= (5/30) = 1/6 of work can be done per day.

Since 1/2 of the work has remained,

(1/2) / (1/6) = 3 days required for A and C to

complete the work.

hope it helps :)