Here’s and example of a SMART MATH problem for AVERAGES.
Problem
The average attendance in a class for the first four days of the week is 32 and for the first 5 days is 33. How many students were present on the fifth day?
- 36
- 37
- 38
- 39
- 40
The Usual Method
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Total attendance of the class for the first 4 days = 32 x 4 = 128
Similarly, total attendance of the class for the first 5 days = 33 x 5 = 165
Hence, number of students on day 5 = 165 – 128 = 37
(Ans: 2)
Estimated Time to arrive at the answer = 45 seconds.
Using Technique
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Simply adding 32 + 5 = 37 gives you the answer.
The reasoning here is that if the average of the first 5 days is 32, than the attendance of the 5th day would be 32. Since the average is 33, 1 day more then 32; than for 5 days it is and extra 5, the additional 1 being true for 5 days. So, it is 32 + 5 = 37.
(Ans: 2)
Estimated Time to arrive at the answer = 5 seconds.
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