1 / 4 of all married couples have more than one child . 1 / 5 of all married couples have more than 3 children . what fraction of all married couples have 2 or 3 children ?
"plug in simple numbers . take 100 couples for example . 1 / 4 of 100 couples have more than one child = 25 couples . 1 / 5 of 100 couples have more than 3 kids = 20 couples . this implies that 20 couples are a subset of 25 couples and the complement of 25 couples within those 100 couples , which equals 75 couples have either one or no kids at all . we need to find couples that have 2 or 3 kids , so essentially , it is 25 - 20 = 5 . fraction will be 5 / 100 = 1 / 20 . option c"
subtract(divide(1, 4), divide(1, 4))