Percentages Smart Math

[Smart Math] Percentages Problem 9

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



With the profit margin increased, a traders earns 25% more than before. If his earnings now are $800 per month, what was it before?

  1. $600
  2. $625
  3. $640
  4. $675
  5. $720

The Usual Method

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Let the earning of the trader initially be $x. With an increase in the margins, the earning is now $1.25x

But 1.25x = $800

\therefore x=\frac{800}{1.25}=640

(Ans: 3)

Estimated Time to arrive at the answer = 30 seconds.

Using Technique

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If earning increase by 25%, to get the original earnings, the new earning should be reduced by 20% (See concept explained in the section of Percentages Stuff to Remember)

Thus old earnings = $800 less 20% = 800 – 160 = 640

Hence option ‘3’.

(Ans: 3)

Estimated Time to arrive at the answer = 10 seconds.
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