Explanation:
To calculate the probability, we need to know the total number of pens of each color. Given that Evelyn has 80 pens in total and 15 of them are black, the remaining pens must be blue.
Probability of picking a black pen:
Number of black pens = 15
Total number of pens = 80
Probability of picking a black pen = Number of black pens / Total number of pens
= 15 / 80
= 3 / 16
Therefore, the probability that Evelyn picks a black pen is 3/16.
Probability of picking a blue pen:
Number of blue pens = Total number of pens - Number of black pens
= 80 - 15
= 65
Probability of picking a blue pen = Number of blue pens / Total number of pens
= 65 / 80
= 13 / 16
Hence, the probability that Evelyn picks a blue pen is 13/16.