how to solve this ques.if x completes a work in 3 hrs and y completes in 4 hrs.if they are working alternatively for 1 hour each.how many hours it will take to complete the work.

Hi Haritha,

Work done by X in one hour = 1/3
Work done by Y in one hour = 1/4
Work done by X and Y in two hours = 1/3 + 1/4 = 7/12
Work done in the third hour = 1/3
Total work done at the end of 3 hours = 7/12 + 1/3 = 11/12
So, time required to complete the remaining work = (1/12)/(1/4) = 4/12 = 1/3 hours
So, total time required = 3.33 hours