what is the probability of getting exactly 2 heads in a single throw of five fair coins ?
"one possible case is hhttt . p ( hhttt ) = 1 / 2 * 1 / 2 * 1 / 2 * 1 / 2 * 1 / 2 = 1 / 32 there are 5 c 2 = 10 possible cases . p ( 2 heads ) = 10 * 1 / 32 = 5 / 16 the answer is d ."
divide(const_2, choose(add(const_3, const_3), const_3))