If 15 pumps of equal capacity can fill a tank in 7 days, then how many extra pumps will be required to fill the tank in 5 days?

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Submitted by examrobotsa on

Q: 135 (IAS/1998)
If 15 pumps of equal capacity can fill a tank in 7 days, then how many extra pumps will be required to fill the tank in 5 days?

question_subject: 

Maths

question_exam: 

IAS

stats: 

0,4,8,4,4,2,2

keywords: 

{'many extra pumps': [0, 1, 0, 0], 'pumps': [0, 1, 0, 0], 'equal capacity': [0, 1, 0, 0], 'days': [0, 0, 2, 0], 'tank': [0, 1, 0, 1]}

The problem deals with inverse proportionality, which means if one quantity decreases, the other quantity increases in order to keep the product constant. Here, the quantities are the number of pumps and the number of days.

From the problem, 15 pumps can fill the tank in 7 days. We need to figure out the amount of pumps needed to fill the tank in 5 days.

For the options:

1. 6 additional pumps would give a total of 21 pumps. This means each day, 21/7 = 3 tanks are filled which will lead to a total of 5x3 = 15 tanks in 5 days. This is the correct answer.

2. 7 additional pumps gives 22 total pumps, filling 22/7 = approx 3.14 tanks each day, leading to over 15 tanks in 5 days. Too many pumps are needed.

3. 14 additional pumps (so a total of 29) will fill even faster than option 2, which is unnecessary.

4. 21 additional pumps (total of 36) is by far too many. This will fill the tank extremely quickly, far surpassing the required 5 days.