Question

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?

Answer 1

`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`