Consider a set S given as {11,22,33,44,55,66,77,88,99} . If each element of the data set is multiplied by -9 then by what factors will the Mean,Variance and Standard Deviation respectively change ? Choices
A) -9,-9,-9	B) -9,9,9	C) 1,1,1	D) -9,81,9	E) 9,9,81
Mean: If all values are multiplied by -9 then their sum will also be multiplied by -9 so Mean will also get -9   Variance:   Variance is equal to (Sum of (Square of (the difference between mean and individual values))/Total number of values   When we multiply all the values by -9 then the difference between the mean and the individual values also gets multiplied by -9 and the square of that difference becomes 81. So, the variance gets multiplied by a factor of 81   SD:   Standard Deviation is the square root of variance so sqrt(81)=9. So SD gets multiplied by a factor of 9.   So, answer will be -9,81,9.
<result>D</result>
Consider a set S given as {11,22,33,44,55,66,77,88,99} . If each element of the data set is multiplied by -9 then by what factors will the Mean,Variance and Standard Deviation respectively change ?