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If the average (arithmetic mean) of 9 numbers is 325, what i

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If the average (arithmetic mean) of 9 numbers is 325, what i

by Max@Math Revolution » Wed Mar 16, 2016 5:28 pm
If the average (arithmetic mean) of 9 numbers is 325, what is the median of them?

1) The average (arithmetic mean) of the 4 smallest numbers of them is 125
2) The average (arithmetic mean) of the 4 largest numbers of them is 500


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by Max@Math Revolution » Sat Mar 19, 2016 10:06 pm
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.


If the average (arithmetic mean) of 9 numbers is 325, what is the median of them?

1) The average (arithmetic mean) of the 4 smallest numbers of them is 125
2) The average (arithmetic mean) of the 4 largest numbers of them is 500


In the original condition, there are 9 variables, which should match with the number of equations. So you need 9 equations. For 1) 1 equation, for 2) 1 equation, which is likely to make E the answer.
When 1) & 2), s1+s2+s3+s4+Median+L1+L2+L3+L4=9*325 is derived. From s1+s2+s3+s4=4*125 and L1+L2+L3+L4=4*500, you can figure out Median in a unique way, which is sufficient. Therefore, the answer is C.
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