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