Hayley runs a day care center. So far this year, the enrollment has consisted of 3
preschoolers and 15 children of other ages. What is the experimental probability that the next
child to enroll will be a preschooler?
Write your answer as a fraction or whole number.
P(preschooler) =

The owner of the plant nursery where you were tells you to fill 350 ml bottles from a 30 l from a fertilizer

In a singing competition, there are 150 participants. at the end of each round, 40% of the participants are eliminated. how many participants are left after n rounds?

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.