Percentage? Please Help

Question

A bag contains 2 red marbles, 3 blue marbles, and 4 green marble. What is the probability of choosing a red marble, and without replacing it, then drawing a green marble? Write your answer as a percentage rounded to the nearest whole.

1) 50%

2) 22%

3) 8%

4) 11%

Answer 1

So we have two consecutive events, therefore we must multiply the separate event probabilities to find the total probability.  

 

The first even is drawing a red marble.  We have 2 red marbles in the bag and 9 total marbles, so the probability of choosing a red marble is 2/9.

 

Next even is choosing a green marble.  Since we are not replacing the first marble in the bag, we now have 8 total marbles to choose from and 4 possible green marbles, for a probability of 4/8, or 1/2.

 

Now we multiply these two probabilities and simplify:

 

2/9 * 1/2 = 2/18 = 1/9

 

Now we divide 1 by 9 to get a decimal answer of .11 repeated.  Turn that into a percent for an answer of 11%.