Question

A spinner is divided into many sections of equal size. Some sections are red, some are blue, and the remaining are green. The probability of the arrow landing on a section colored red is 9 over 20. The probability of the arrow landing on a section colored blue is 6 over 20. What is the probability of the arrow landing on a green-colored section?
15 over 20
11 over 20
6 over 20
5 over 20

Answer 1

Well.... If you already know that the probabilities of landing on red or blue is 9 and 6 over 20, just add them together and you should get 15/20. Now you know that there is only 5/20 left over. SO 5 over 20 is your answer. Hope that helps.

Answer 2

Well they are fractions, you want to add them and see what is left. If you would add them together you have to have the same denominator. It already is saying 20. Something over something is dividing it by the second number, also known as a fraction. 9/20 + 6/20 / 15/20. Now 20/20 = 1. You want to find green which is 5/20. So the answer is D. 5 over 20.