Answer:
0.4 = 40% probability the marble is even numbered given the marble is yellow.
Explanation:
A probability is the number of desired outcomes divided by the number of total outcomes.
In this question:
There are 5 yellow marbles, which means that the number of total outcomes is

2 of those(2 or 4) are even numbered, which means that the number of desired outcomes is

Find the probability the marble is even numbered given the marble is yellow.

0.4 = 40% probability the marble is even numbered given the marble is yellow.