If it is assumed that 70 percent of those who receive a questionnaire by mail will respond and 300 responses are needed, what is the minimum number of questionnaires that should be mailed? Select.
A) 400
B) 428.5
C) 480
D) 500
E) 600

Rationale: "minimum no of mail to be sent for getting 300 responses at 70 % = 300 / 0.7 = 428.5 option b"
Answer: B