Question

If 55% of a number is 132 and 25% of the same number is 60, find 80% of that number.

Answer 1

Answer:

  192

Step-by-step explanation:

It is always wise to look carefully at the question to see what information is given, and what information you are asked for. You are given two different fractions of the same number, and you want the value of a third fraction of that number. That third fraction is the sum of the other two.

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The value of 80% of the number will be the sum of 55% and 25% of the number.

  n×80% = n×55% +n×25%

  n×80% = 132 +60

  n×80% = 192

80% of the number is 192.

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Additional comment

Your first clue that there may be something special about this problem lies in the fact that one fraction of a number is all you need in order to find any other fraction. Here, we're given two fractions (55% and 25%), so that is more information than we need. Why? Because it simplifies the problem to one of addition. No proportions need to be solved.

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If you were interested, you could determine 100% of the number to be ...

  132/n = 55/100   ⇒   n = 132(100/55) = 240

or

  60/n = 25/100   ⇒   n = 60(100/25) = 240

Then ...

  0.80n = 0.80(240) = 192 . . . . 80% of the number

Or, you could write proportions for the 80% value:

  80%/55% = n/132   ⇒   n = 132(80/55) = 192 . . . . 80% of the number

  80%/25% = n/60   ⇒   n = 60(80/25) = 192 . . . . 80% of the number

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"Look carefully" includes thinking about the ways the givens and the finds are related.