Question

a water tank can be filled in 7hours by 5 equal sized pumps working together. how much time will 7 pumps take to fill it up

Answer 1

Let assume tank capacity =7x5=35
So 7 will fill it =35/7=5 hr
In 5hr tank will be filled by 7 pumps

Answer 2

Concept

The unitary method is a method in which you find the value of a unit and then the value of a required number of units. What can units and values be .

Given

We have given that 5 pumps take 7 hours to fill the water tank.

Find

We are asked to determine the time in which 7 pumps takes to fill the water tank .

Solution

Tank capacity is V liter .

It is given that it takes 7 hours for 5 pumps to fill V liters .

5 pumps  fill V liters in 7 hours

5 pumps  fill (V / 7) liters in 1 hour

One pump fills ((V / 7) / 5) liters in one hour

One pump fills V / 35 liters in 1 hour

Them time taken by the 7 pumps will be

7 pumps  fill 7 (V / 35) liters in 1 hour

7 pumps  fill V / 5 liters in 1 hour

7 pumps  fill 5 (V / 5) liters with 5 (1 hour)

7 pumps  fill V liters in 5 hours

Therefore, 7 pumps will take 5 hours to fill it up .

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