A rectangular tank 15 m long and 11 m broad is required to receive entire liquid contents from a full cylindrical tank of internal diameter 21 m and length 5 m. find the least height of the tank that will serve the purpose.
Volume of liquid in the new rectangular tank = volume of liquid filled in full cylindrical tank
lbh = π r2 h’
Here, r = 
m, h’ = 5m, l = 15m and b = 11m, then
16