A survey was sent to 70 customers, 7 of whom responded. Then the survey was redesigned and sent to another 63 customers, 9 of whom responded. By approximately what percent did the response rate increase from the original survey to the redesigned survey? Choices.
A) 2 %
B) 6 %
C) 4 %
D) 28 %
E) 63 %

Rationale: case 1 : ( 7 / 70 ) = x / 100 x = 10 % case 2 : ( 9 / 63 ) = y / 100 y = 14 % so percent increase is = ( y - x ) = ( 14 - 10 ) % = 4 % answer is c
Answer: C