A bag contains 5 blue marbles, 2 black marbles, and 3 red marbles. A marble is randomly drawn from the bag.
The probability of not drawing a black marble is
. The probability of drawing a red marble is
.
Since you are not allowed to draw a black marble, then you have only 7 ways to draw either a blue or a red marble. The sum of all marbles is 10. So the probability of not drawing a black marble is 7/10 and the probability of drawing a red marble is 2/10 or 1/5.
