Three unbiased coins are tossed. What is the probability of getting at most two heads?
Choose the correct choice from the following answers.
A) 3 / 4	B) 1 / 4	C) 3 / 8	D) 7 / 8	E) none of these

Rationale: explanation : here s = { ttt , tth , tht , htt , thh , hth , hht , hhh } let e = event of getting at most two heads . then e = { ttt , tth , tht , htt , thh , hth , hht } . p ( e ) = n ( e ) / n ( s ) = 7 / 8 . answer is d
Answer: D