Here’s and example of a SMART MATH problem for RATIO PROPORTION.
Problem
A certain sum of money is divided between A, B and C in the proportion of 2 : 3 : 4. If C were to give B $20, and B were to give A half of what he has now, the amounts which A and C have now would be same. What is the amount divided between the three?
- $420
- $480
- $500
- $540
- $600
The Usual Method
[contentblock id=google-adsense-post]
Let the shares of A, B and C be 2x, 3x and 4x respectively. (where ‘x’ is the constant of proportionality)
Thus,
(4x – 20) is the new share of C
is the new share of B and
2x + is the new share of A.
Also, since new shares of A and C are equal:
2x + = (4x – 20)
Hence total sum = $540
(Ans: 4)
Estimated Time to arrive at the answer = 60 seconds.
Using Technique
[contentblock id=google-adsense-post]
Total sum of money to be shared = . Hence the sum should be a multiple of 9. Only option ‘4’ ($540) is a multiple of 9. This eliminates all the other options, so option ‘4’ is the answer.
(Ans: 4)
Estimated Time to arrive at the answer = 5 seconds.
[starrater tpl=10]
[contentblock id=smartmath-blockquote]