Only 40% of the students in a certain liberal arts college are males. if two students from this college are selected at random, what is the probability that they are of the same gender?

Charlie is at an amusement park that has 18 different rides. each ride costs $1.75. the function c(r) = 1.75r represents the total amount of money that charlie will spend if he goes on r rides, but he never goes on the same one more than once. what domain and range are reasonable for the function?