RRB Group-D Model Paper 19 with answers for online practice

Given:
Pipe X can fill a tank in 12 hours and pipe Y can fill the same tank in 36 hours
Formula used:
Time taken to fill = total work/one hour’s work
Calculation:
Pipe X → 12 hours
Pipe Y → 36 hours
On taking LCM (12, 36), Total work = 36
One hour’s work of Pipe X = 36/12 = 3
One hour’s work of Pipe Y = 36/36 = 1
One hour’s work of (X + Y) = 3 + 1 = 4
∴ Time taken by (X + Y) together fill full tank = 36/4 = 9 hours
⇒ Time taken by (X + Y) together fill one-third part of the tank = 9/3 = 3 hours