Complete 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 11 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?
Answer: 3/20
Step-by-step explanation:
From the question, the spinner is divided equally into sections painted with 3 different colors (RED, BLUE and GREEN)
Given that:
P(arrow landing on red) = 11 / 20
P(arrow landing on blue) = 6/20
The probability of arrow landing on green is therefore :
Sum of the probabilities of red and blue :
P(arrow landing on red) + P(arrow landing on blue)
= (11/20 + 6/20) = 17/20
Recall : The sum of probabilities of mutually exclusive events must sum up to 1. Therefore, since the events represented above are mutually exclusive, that is no two events can occur at the same time.
Then:
P(arrow landing on red) + P(arrow landing on blue) + P(arrow landing on green) = 1
Hence,
P(arrow landing on green) = 1 - [(P(arrow landing on red) + P(arrow landing on blue)]
P(arrow landing on green) = 1 - [11/20 + 6/20]
P(arrow landing on green) = 1 - 17/20
P(arrow landing on green) = 3/20
