three unbiased coins are tossed . what is the probability of getting at least 2 tails ?
"explanation : s = { hhh , hht , hth , htt , thh , tht , tth , ttt } e = { htt , tht , tth , ttt } n ( s ) = 8 n ( e ) = 4 p ( e ) = n ( e ) / n ( s ) = 4 / 8 = 0.5 answer is b"
negate_prob(divide(const_1, power(const_2, const_3)))