Question

Using the bag of marbles below, find the probability of pulling a red marble two times in a row. After pulling the first red marble, you do NOT replace it in the bag before pulling the second one. Each marble has an equally likely chance of being pulled.

A. 10/21
B. 5/7
C. 25/51
D. 4/63​

Answer 1

A. 10/21

Explanation:

There is a total of 7 marbles, 5 of which are red ---> 5/7

When you pull out a red marble and do not replace it in the bag before pulling the second one, a marble (red) is gone hence ----> 4/6

Multiply the two events to find the probability:

5/7 x 4/6 = 10/21