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Re: A big container is 30% full with water. [#permalink]
03 Feb 2012, 19:19

3

This post received KUDOS

This is a classic two equations, two unknowns type question. You could set up two equations, and use brute fore to solve. BUT, this is not what a smart test taker should do. Pattern recognition is what's being tested here.

Notice that answers A, B, and E, are divisible by 4, the others are no. So you can eliminate choices C, and D since 3/4 of these choices will not result in a whole number.

Since the answer choices are in chronological order, test the middle choice - choice B

notice that 3/4 of 40 is 30. Easy. If you subtract 18 from 30, you get 12. 12/40 reduces to 3/10 - 30%. Voila choice B satisfies the conditions of the question. Choice B is the correct answer.

Remember the GMAT isn't designed to test your math skills, it's designed to test critical thinking and your ability to recognize patterns and find the easy way of solving a problem. Look for the easy answers.

Re: A big container is 30% full with water. [#permalink]
03 Feb 2012, 22:30

1

This post received KUDOS

30% full with water can be written as 30C/100 or 3C/10 , where C is the capacity of the cylinder 18 liters of water is added, the container becomes 3/4 full 3C/10 + 18 ltr = 3C/4 3C/4 - 3C/10 = 18 ltr C = 40 ltr B is correct try doing this question in ur mind..it will help u speed up the calculation and save time. _________________

Fire the final bullet only when you are constantly hitting the Bull's eye, till then KEEP PRACTICING.

Re: A big container is 30% full with water. [#permalink]
04 Feb 2012, 05:35

1

This post received KUDOS

Expert's post

nafishasan60 wrote:

A big container is 30% full with water. If 18 liters of water is added, the container becomes 3/4 full. What is the capacity of the big container?

A) 36 liters B) 40 liters C) 45 liters D) 54 liters E) 60 liters

A big container is 30% full with water and after 18 liters of water is added, the container becomes 75% full. Hence these 18 liters account for 45% of the container, which means that the capacity of it is 18/0.45=40 liters.

OR: if the capacity of the container is x liters then: 0.3x+18=0.75x --> x=40 liters.

Re: A big container is 30% full with water. If 18 liters of [#permalink]
03 Jun 2014, 11:33

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