A bag contains 5 red, 3 brown,6 yellow, and 2 blue marbles. Once a marble is selected, it is not replaced. Find the probability of pulling a red marble, and then a blue marble?

1 Answer
Mar 12, 2018

7/240

Explanation:

First establish the probability of pulling out each colour from a full bag.
P(r) = (n(r))/(n(s)) = 5/16
P(br) = (n(br))/(n(s)) = 3/16
P(y) = (n(y))/(n(s)) = 6/16
P(bl) = (n(bl))/(n(s)) = 2/16
Where s is the sample space.
The probability of pulling out a red marble is 5/16.
Now the sample space (s) is reduced by one, as a red marble has been removed. The new s value is 15.
Therefore, the probability of pulling out a blue marble is now 2/15.
To find the probability of fulfilling both of these conditions, we multiply the probabilities:
5/16 * 2/15 = 7/240