RRB NTPC Mains or Stage 2 Model Paper 3 with solutions

Question : 30 of 120

Marks: +1, -0

Pipe A alone can fill a tank in 8 hours. Pipe B alone can fill it in 6 hours. I f both the pipes are opened and after 2 hours Pipe A is closed, then the other pipe will fill the tank in

6 hours
$3 1/ 2$ hours
4 hours
$2 1/ 2 hours$

Validate

Solution:

Par t of the tank filled by both pipes in two hour

=2[1/8+1/6]=2[3+4/24]=7/12

Remaining part =

1-7/12=5/12

Time taken by B to fill the remaining part

= 5/12×6=21/2 hours

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