Alice's belt rack contains 1 red, 3 black, 4 brown, and 2 blue belts. If she were to randomly select one belt from the rack, what is the probability that it would be black?

An irrigation system for a small farm uses 750 gallons of water per hour. The system was turned on for 5 consecutive days for the following numbers of hours: 4.5, 8, 6.5, 2.5, and 8. What was the mean (average) number of gallons of water used daily by the irrigation system during those 5 days?

Angie bought a snack pack of candy at the store. The pack has 24 candies in all, with 6 blue, 5 red, 7 orange, 2 brown, and 4 green pieces. If she reaches into the bag without looking, what is the probability that she would choose a brown piece of candy?

If 3x + 30 = 9x, what is the value of x?

A library features its new books on a cart. The new books this month are 12 mystery books, 6 biographies, and 2 poetry collections.
If Donald randomly selects a book from the cart, what is the probability that he will select a poetry collection?