# Basic Math MCQ 16 (Taps filling a tank and their rate of filling)

MCQ 16: Two taps X and Y can fill a tank in 10 hrs. and 15 hrs.respectively.  If the both taps are opened together, the tank will be full in_________?

a) 3 hrs.             b) 4 hrs,                 c) 5 hrs.                    d) 6 hrs.

Solution:

We know rate of doing some work is  calculated by dividing work by time taken.

For example If a car is covering a distance of 20 km in 1 hour then we say its rate of running (speed) is 20 km / hour !

Similarly we calculate filling rate of both tapes !

Tap X

Tap X can fill a tank in 10 hurs ===> rate of filling of Tap X = 1 (tank)/10 hour = 1/10 hour

Similarly.

Tap Y

Tap Y can fill a tank in 15 hours ====> rate of filling of Tap Y = 1 (tank)/15 hours = 1/15 hours

If both taps are opend together ;

Rate of Tap X + TapY = 1/10+1/15 = 5/30= 1/6 hours

I-e Both taps can fill the tank in 6 hours !

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