Pipes A, B and C can fill a tank alone in 20, 30 and 50 hours respecitvely. If all three pipes are open simultaneously, in how much time will the tank get half filled?
1) 30 hr
2) 5 1/5 hr
3) 4 26/31 hr
4) 6 1/31 hr
The numbes x, y, z are proportional to 2, 3, 5. The sum ,of x, y, z is 100. If y ;= px - 10, then p is equal to
1) 3/2
2) 2
3) 5/2
4) 3
