The probability of selecting a pencil of a certain color is given by the amount of pencils of that color over the total number of pencils.
Knowing that, let's first calculate the total number of pencils:
Then, the probability of selecting a blue pencil is:
And the probability of selecting a yellow pencil is:
Now, to calculate the probability of both events happening, we just need to multiply the probabilities of each event:
So the probability is 0.09 or 9%.