calculate the standard deviation of each data set { 10 , 1010 , 1010 }  Choose the correct choice from the following choices:  A) 8.05  B) 9  C) 10  D) 15  E) 15.5

Rationale: standard deviation data set a = √ [ ( ( 9 - 10 ) 2 + ( 10 - 10 ) 2 + ( 11 - 10 ) 2 + ( 7 - 10 ) 2 + ( 13 - 10 ) 2 ) / 5 ] = 2 standard deviation data set b = √ [ ( ( 10 - 10 ) 2 + ( 10 - 10 ) 2 + ( 10 - 10 ) 2 + ( 10 - 10 ) 2 + ( 10 - 10 ) 2 ) / 5 ] = 0 standard deviation data set c = √ [ ( ( 1 - 10 ) 2 + ( 1 - 10 ) 2 + ( 10 - 10 ) 2 + ( 19 - 10 ) 2 + ( 19 - 10 ) 2 ) / 5 ] = 8.05 option a
Answer: A