GMATPrep Q8

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Source: — Data Sufficiency |

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by amitabhprasad » Thu Dec 25, 2008 4:15 pm
Average of the set of evenly spaced consecutive integers = (1st no + last num)/2
from stmt 1 ; (a1+a9)/2 = 7 ==> a1+a9 = 14
since numbers are consecutive we can find a1, a9 and subsequently others.
sufficient
from stmt 2: a3+a11 = 9*2
from the same above reasoning --> sufficient
hence "D"