A card is drawn from a deck of cards numbered one through twenty. The card is NOT replaced and another card is drawn. Find the probability that a prime number is drawn and then a composite number.
there are 20 cards, between the 20 first numbers,there are 8 primers numbers
so the probability that the first card is primer is 8/20=2/5
after one card is out,they are 19 cards left,and between those cards,there are there are 11 composite numbers....the probability that the second one is a composite card is 11/19