Solution: 1 hour's work of P+ Q + R =( 1/8 + 1/10 +1/12 ) =37/120
work done in 2 hour by P ,Q & R = ( 37/120 ) × 2 = 37/60
Remaining work = 1 - 37/60 =23/60
1 hours work of Q + R =1/10 + 1/12 =11/60
work done Q & R in 1 hour is 11/60
23/60 will be the work done by Q and R in ( 23/60 )× (60/11) =23 /11
So approximately the work will be finished 2 hours after 11 A.M i.e around 1 P,M Ans