Question

if 12 pumps can empty a resevour in
20 hours, then time required by 45 such
pumps to empty the same resevoir is
​

Answer 1

let no. of hours taken by 45 pumps be x

first case,

no. of pumps = 20

no. of hours = 12

second case,

no. of pumps = 45

no. of hours = x

hence, direct variation as less pumps in less time

20/12=45/x

20×x=12×45

20x = 540

x=540/20

x=27

Answer 2

Answer:

16/3 hours

Step-by-step explanation:

Let the total work to be done be x

Let the speed of one pump be s:

Then; 12×20×s=x

work done by 1 pump in 20hours=20s=x/12

work done by 1 pump in 1 hour= s=x/240

work done by 45 pumps in one hour= x/240×45=3x/16

There fore time taken to completely empty the tank =16/3 hours

another way to do it is

12×20=45×t

16=3t

16/3=t

hope it helps please mark brainliest and happy new year.