Math Help - Help probability

1. Help probability

A bag of marbles is filled with red and blue marbles. There are 24
marbles in the bag. The probability of Pete picking a blue marble
out of the bag is 3/4.How many blue marbles are in the bag? What is
the probability that pete picks a red marble?

2. Originally Posted by star29867
A bag of marbles is filled with red and blue marbles. There are 24
marbles in the bag. The probability of Pete picking a blue marble
out of the bag is 3/4.How many blue marbles are in the bag? What is
the probability that pete picks a red marble?
If you have a 3/4 chance of picking out a blue marble, than 4/4 of the marbles are blue.

So: $24\times\frac{3}{4}=18$

And obviously there's a 1/4 chance he'll pick a red marble.