If it is assumed that 60 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?
Choose the correct choice from the following choices:  A) 400  B) 420  C) 480  D) 500  E) 600

Rationale: "minimum no of mail to be sent for getting 300 responses at 60 % = 300 / 0.6 = 500 option d"
Answer: D