Question

A bag contains 4 black and 3 pink balls. A ball is picked from the bag and is not replaced. A second ball is then picked from the bag.

The tree diagram below can be used to calculate various probabilities.
What is the probability of picking one
ball of each colour?
A
4/49
B
24/42
C
1/2
D
12/42

Answer 1

1/2

Explanation:

There are 4 possibilities:

First ball Second ball

1. Black Pink

2. Black Black

3. Pink Pink

4. Pink Black

The first and the forth options are the the probabilities that there is picked one ball for each color. (2 possibilities )

The second and the third options are the probabilities that there ate picked 2 balls of same colour.

(2 possibilities)

There are 4 possibilities in total. So the probability is 2/4=1/2