1. Tells us that x is the median and can= 8,9,10. We're told that the median=mean, so we can plug in each value (8,9,10) into the rest of the set to find the average. The number that makes the mean=median is the correct answer. If there's more than one correct answer the statement is insufficient:
Again, we know that x is the median, we're trying to find the value that makes the average of the set equal to the median
using x= 8:
(2+7+8+11+16)/5 does not = 8
x=9
(2+7+9+11+16)/5 does = 9
x= 10
(2+7+10+11+16)/5 does not=10
Because 9 is the only value that works, the statement is sufficient
2. Says the same thing as the Statement 1 (x=8,9 or 10) so we know it's sufficient.
Thus, D is the answer.
Hope that helps
value of x
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gmat_nov_2008
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pseudononymous
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(1) This tells you that x is the mean. Whenever the the mean=median, the numbers are normally distributed. This tells you that x has to be equally spaced between 7 and 11, which means that it's 9.
(2) See above
(2) See above
