A

SD is measure of the variations of the elements of set with respect to mean.

Lets say water tanks have

10 , 20 , 30, 40, 50 , 60 gallons

Now after removing 30% from each we have

7,14,21,28,35,42

As all elements are reduced by 30%, the mean will also be reduced by 30%. So the variation of elements with respect to the new mean is also same. So SD will remain the same.

statement 2 don't tell the scenario after the removal. So its INSUFF.

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SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008