RRB Paramedical Staff Nurse Model Paper 3

Question : 51 of 100

Marks: +1, -0

Two inlet pipes P and Q can fill a tank in 24 minutes and 32 minutes respectively. If both the pipes are opened simultaneously, after how much time should Q be closed so that the tank is full in 18 minutes ?

6 min
8 min
10 min
11 min

Validate

Solution:

1 minute work of

({P}+{Q})

both

=(\;{1}/{24}+\;{1}/{32})

=\;{4+3}/{8 × 12}=\;{7}/{96}

minutes
i.e. tank will full in

\;{96}/{7}

minutes.
Let Q is closed after x minutes
∴ rest work

=(1-\;{7 x}/{96})

done by P
p → 24 minutes → 1

∴ (1-\;{7 x}/{96}) → 24(1-\;{7 x}/{96})

∴ 24(1-\;{7 x}/{96})=(18-x)

⇒ 24-\;{7 x}/{4}=18-x

⇒ 6=\;{3 x}/{4} \;\; ⇒ x=8

minutes

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