math
posted by nnnnn on .
In a drawing for a DVD player, there are 100 tickets in a box. Five of the cards are marked with a star and the rest are marked with an X. To win, Carmen must draw two cards, without replacement, both of which are marked with a star. What is the probability that Carmen will win the DVD player?
1/500 ?

She has to draw one of 5 star cards out of 100, AND a second one of 4 star cards out of 99.
5/100 for the first AND 4/99 for the second.
To achieve both outcomes, the probabilities are multiplied together to get
(5÷100)*(4÷99)
=1/495