# If 12 pumps can empty a reservoir in 20 hours, then time required by 45 such pumps to empty the same reservoir is ______ hours

**Solution:**

__Pumps__ __Time taken to empty__

12 20 hours

45 x = ?

More the pumps the faster will be the rate emptying the reservoir. Therefore inverse proportionality is established here.

x = 20 × 12/45

x = 4 × 12/9

x = 4 × 4/3

x = 16/3 or 5 1/3 hours

**✦ Try This: **If 6 pumps can empty a reservoir in 15 hours, then time required by 30 such pumps to empty the same reservoir is ______ hours.

__Pumps__ __Time taken to empty__

6 15 hours

30 x = ?

More the pumps, the faster the rate of emptying the reservoir. Therefore:

x = 15 × 6/30

x = 15 × 1/5

x = 3 hours

**☛ Also Check: **NCERT Solutions for Class 8 Maths Chapter 13

**NCERT Exemplar Class 8 Maths Chapter 10 Problem 25**

## If 12 pumps can empty a reservoir in 20 hours, then time required by 45 such pumps to empty the same reservoir is ______ hours

**Summary:**

If 12 pumps can empty a reservoir in 20 hours, then time required by 45 such pumps to empty the same reservoir is __5 1/3 __hours

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