Here’s and example of a SMART MATH problem for RATIO PROPORTION.
Problem
The income of Jack and Jill are in the ratio of 2 : 3 and their expenses are 3 : 5. If both save $2000, what is Jill’s income?
- $15000
- $12000
- $10000
- $8000
- $6000
The Usual Method
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Income of Jack = 2x
Income of Jill = 3x
Also expense of Jack = 3y
And expense of Jill = 5y
Substituting this in the, we get:
Income of Jill = 3 x 4000 = $12000
(Ans: 2)
Estimated Time to arrive at the answer = 45 seconds.
Using Technique
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Jill’s income is 3x, hence it is a multiple of 3.
This eliminates options ‘3’ and ‘4’.
Now, after removing the savings from the income, we get expenses. Expenses for Jill is 5y.
Hence, 15000 – 2000 = 13000 (13 is not a multiple of 5)
12000 – 2000 = 10000 (10 is a multiple of 5)
6000 – 2000 = 4000 (4 is not a multiple of 5)
Hence option ‘2’.
(Note: All numbers are taken in their ‘000s as 2000 is in ‘000).
(Ans: 2)
Estimated Time to arrive at the answer = 15 seconds.
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