RRB Group D 17-Dec-2018 Shift 1 Soled Paper

In 2 hours cistern will be empty by = 2 + (-3 ) = - 1unit
When starting from B and followed by A. 2 hours→ 1 unit out
15 x 2 hours → 1 5 x 1 unit out
30 hours→ 15 units
Total capacity= 17.4 units
Left= 17.4-15 = 2.4
Now B is open for 31st hours and its efficiency is 3 unit/hour but left water is 2.4.
So, Time taken=

2.4

3

×60 minutes.