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Percentages Smart Math

[Smart Math] Percentages Problem 19

Here’s and example of a SMART MATH problem for PERCENTAGES.

Percentages

Problem

The annual increase in population of a town is 5% If the present population is 70560, what was it two years ago?

  1. 64000
  2. 64500
  3. 66000
  4. 66500
  5. 67000

The Usual Method

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Let the population of the town two years ago be ‘x’.

Hence, population now will be:

x\times 1.05\times 1.05=70560

\therefore x=\frac{70560}{1.05\times 1.05}=\frac{70560}{1.1025}=64000

(Ans: 1)

Estimated Time to arrive at the answer = 45 seconds.

Using Technique

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The two 5% increases can be looked at approximately 10% increase. Reducing 10% from 70560, we get: 70560 – 7056 = 63560 which is closest to 64000. Hence option ‘1’.

(Ans: 1)

Estimated Time to arrive at the answer = 10 seconds.
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