Here’s and example of a SMART MATH problem for RATIO PROPORTION.
Problem
Three men or six women do a piece of work in 20 days. In how many days can 12 men and 8 women do the same piece of work?
days
days
days
days
days
The Usual Method
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3 men = 6 women
1 man = 2 women
Hence 12 men = 24 women
Hence 12 men and 8 women = 24 women and 8 women = 32 women.
If 6 women take 20 days, 32 women would take days
= days.
(Ans: 3)
Estimated Time to arrive at the answer = 45 seconds.
Using Technique
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We know that 3 men take 20 days, so 6 men would take 10 days (1/2 of 20 days), so 9 men would take 1/3 of 20 days i.e days and so on.
We also know that 8 women = 4 men, hence total number of men = 12 + 4 = 16 men.
Approximation 16 to 15 men, and 15 men is same as 5 times of 3 men, so 15 men would take days. Since actual number of men is more than 15, actual number of days will be slightly less than 4, so
days.
(Ans: 3)
Estimated Time to arrive at the answer = 10 seconds.
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