TS ICET 2015 Question Paper with Solutions for online practice

Question : 105 of 200

Marks: +1, -0

Pipes A, B, C can fill a tank individually in 2 hours, 3 hours and 4 hours respectively. All the three are opened for 15 minutes and pipe C is closed. The time (in minutes) required further to fill the tank is

48
52 $1/2$
54
70

Validate

Solution:

Part of tank filled in 15 min. i.e.;

1/4

={1}/{4}({1}/{2}+{1}/{3}+{1}/{4})={6+4+3}/{4×12}={13}/{48}

Remaining empty part of the tank

1-13/48=35/48

∴ Additional time taken by (A + B) to fill the remaining part of the tank,

=(35/48)/(1/2+1/3)35/48×6/5=7/8=

=7/8×60\minute=105/2\min=52{1/2}

minute

Aliter: Let the additional time be t minutes.

∴({t+15}/{2×60})+({t+15}/{3×60})+({15}/{4×60})=1

{6t+90+4t+60+45}/{720}=1

⇒10\t=720-195

t=525/10=52.5=52{1/2}

minutes

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