Mary has a stack of cards, 8 purple, 6 orange, 5 red and 7 black. If she has to choose a card, how many possible outcomes are there?

Yao xin puts 3/10 liters of potting soil in each pot for planting flowers. she has 5 2\3 liters of potting soil. how many pots can yao xin fill?

(if f(x)=4x^2 and g(x)=x+1, find (f o g)(x)

Reduce fractions expressing probability to lowest terms. in 3,000 repetitions of an experiment, a random event occurred in 500 cases. the expected probability of this event is?