Suppose we pick 2 balls out of a box with
replacement. Let's say 8
are red
and 6
are blue.
What is the probability of picking a
red ball then a blue
ball?
| Solve |
Step |
| Pick red first. Pr(red) = 8/14 |
There are a total of 14 balls in the box. |
|
Then pick blue. Pr(blue) = 6/14 |
The number of balls is not reduced because the question said with replacement. The first ball is put back into the box. |
|
Pr(red then blue) = 8/14 × 6/14 = 48/156 = 12/49 |
These events are independent |