if 4 people are selected from a group of 9 married couples , what is the probability that none of them would be married to each other ?
if we are to select 4 people from 9 couples without any restriction , how many ways can we make the selection ? 18 ! / 4 ! 14 ! = 3060 if we are to select 4 people from 9 couples with restriction that no married couple can both make it to the group , only a representative ? 9 ! / 4 ! 5 ! = 126 but we know that to select a person from each couple , take 2 possibilities 126 * 2 * 2 * 2 * 2 = 2016 probability = desired / all possibilities = 2016 / 3060 = 56 / 85 answer : d
multiply(multiply(multiply(divide(multiply(9, const_2), multiply(9, const_2)), divide(multiply(const_4, const_4), subtract(multiply(9, const_2), const_1))), divide(subtract(multiply(const_4, const_4), const_2), multiply(const_4, const_4))), divide(subtract(subtract(multiply(const_4, const_4), const_2), const_2), subtract(multiply(const_4, const_4), const_1)))