Question

Robin randomly selects a number between 1 and 20. What is the probability that the number selected is the square of a natural number?

Answer 1

You just have to divide the number of positive outcomes with number of all possible outcomes.

Positive outcomes -> squares of a natural number -> 1 (square of 1), 4 (square of 2), 9 (square of 3), 16 (square of 4)

All possible outcomes -> 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20

Feel free to ask more questions if you don't understand;)