Question

A and B take 9 hours and 6 hours, respectively to polish a wooden table .A works for 2hours and then B works for 1 hour .how much work is still left.

Answer 1

Two methods are there
1.)total work =LCM(9,6)unit =18 unit
A takes 9 hrs to finish 18 unit of work
So,he will complete 4unit of work in 2hrs.
B takes 6 hrs to complete the 18 unit of work
So,he will complete 3 unit of work in 1hr
Total work done =(4+3)=7 unit
Work remaining=(18-7)=11 unit
Part of work remaining=11/18
2nd method)A takes 9 hrs to complete work .
So,work completed by him in 2 hrs =2/9
And B takes 6 hrs to complete the work,so he will complete=1/6 work
They both will do=1/6+2/9=3+4/18=7/18 part of work
Work remaining=11/18 part
Hope it helps