Trick of the Day - Arithmetic Mean

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Trick of the Day - Arithmetic Mean

Post by Ani on Thu Feb 26, 2009 6:07 pm

This trick saves some time on questions which ask for you to find the average of two numbers

ex.1 - Find the average of 25, 27, and 35
1. First, think of a number which is a multiple of ten which could be the average (let's say 30 in our case)
2. Secondly, subtract that number from each of the original numbers (25-30 = -5, 27-30 = -3, 35-30 = 5)
3. Add together the above answers (-5-3+5 = -3)
4. Divide the number by the number of terms (-3/3 = -1)
5. add the resulting numer(-1) and the approximation together (-1 + 30 = 29) and you have your answer
Find the average of 25, 27, and 35 = 29

Keep in mind that this trick works for more than just three numbers, as stated above in the steps

Now, try some practice problems
1. AVG(19, 21, 25)
2. AVG(12, 33, 25)
3. AVG(19, 21, 43, 34)
4. AVG(62, 63, 58)
5. AVG(85, 80, 97)
6. AVG(27, 31, 25)
7. AVG(11, 12, 13, 9, 7, 15)
8. AVG(99, 101, 110)
9. AVG(118, 121, 125)
10. AVG(120, 121, 125, 121, 115)
11. AVG(131, 135, 125, 140)
12. AVG(1435, 1351)
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