Question

there are two taps in a cistern the first tap can fill 4 / 5 of the tank in 3 hour and the second tap can fill half of the tank in 2 hour 30 minutes if both the taps are opened together then in how much time 7 / 10th of the tank will be filled. ( please do step by step explanation. ans. 1hr 30min)​

Answer 1

Answer:

1.5 hours

Step-by-step explanation:

Tank A can fill 4/5 tank in 3 hours.

In one hour, it can fill (4/5)/3=4/15 of tank

Tank B can fill 1/2tank in 2.5 hours.

In 1 hour, it can fill (1/2)/2.5=1/5 of tank

In 1 hour , A and B can fill 4/15+1/5 = 7/15 of tank

They can fill 7/15 of tank in 1 hour

So they can fill 7/10 of tank in 1/(7/15)*(7/10)

= 15/7 *7/10= 15/10=1.5 hours