In how many ways can an answer key for a quiz be written if the quiz contains 5 true-false questions followed by 2 multiples-choice questions with 4 answer choices each, if the correct answers to all true-false questions cannot be the same? Choose the correct choice from the following answers:
A) 160	B) 320	C) 480	D) 600	E) 720

Rationale: there are 2 ^ 5 = 32 possibilities for the true - false answers . however we need to remove two cases for ttttt and fffff . there are 4 * 4 = 16 possibilities for the multiple choice questions . the total number of possibilities is 30 * 16 = 480 . the answer is c .
Answer: C