Question

Joan can do an entire job in 12 hours.ken can do an entire job in 6 hours.if joan and ken work together for 3 hours.how many hours will it take ken to finish the rest of the job by himself

Answer 1

Acc to question,

Joan can finish the work in 12 hours, that means in 1 hour Joan can finish 1/12th part of the work.

Ken can finish the work in 6 hours, that means in 1 hour Joan can finish 1/6th part of the work.

When they work together for 3 hours = 3 x 1/12 + 3 x 1/6 = 1/4 + 1/2 = 3/4. That means 1/4th part of the work is left.

Now according to question, if ken works for t hours then 1/4th part work will be done.

t x 1/6 = 1/4

or, t = 3/2 = 1.5 i.e. 1 hour 30 minutes. (Ans)