A teacher chooses 3 pens. The teacher randomly guesses a pen to use on an assignment. He, he will keep it. Draw a tree diagram to find the probability that the teacher picks a black pen.

Here's the solution to your probability problem.

Step 1: Interpret the problem statement.
The first line is difficult to read, but based on the context of probability problems and the questions asked, we will interpret it as: "A teacher has 8 pens, 3 of which are red." This implies the remaining pens are black.
So, we have:

• Total pens = 8
• Number of red pens (R) = 3
• Number of black pens (B) = $8 - 3 = 5$

The teacher picks a pen and keeps it, meaning the selections are without replacement.

a) Draw a tree diagram to represent the outcomes.

• First Selection: *