One of the 21 dots on a standard die is randomly chosen and colored red. Then the die is rolled. What is the probability that the red dot appears on top?

Question

I know the answer is 1/6 but I don't know the solution.

Answer 1

There are 6 faces on the die.

 

The red dot is on one of those 6 faces.

 

So the probability that that face appears is 1/6