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Is the average (arithmetic mean) of 5 different positive

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Source: — Data Sufficiency |

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by Ian Stewart » Wed May 01, 2019 2:23 am

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A

B

C

D

E

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If the five numbers are, as Statement 1 and the stem tell us, five different positive multiples of 10, the smallest values we could possibly have are:

10, 20, 30, 40, 50

That's an equally spaced list, so its average is equal to its median, so the average of the list above is 30. But that's the smallest possible average we can get, so any list we can make consisting of five distinct positive multiples of ten must have an average of 30 or greater, and Statement 1 is sufficient.

In Statement 2 we can divide 160 by 5 and compute the exact value of the average, so of course we can answer any question about the average, and Statement 2 is sufficient. So the answer is D.
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