The probabilities that a spinner lands on red, blue or green are , and . The spinner can only land on these three colours. What is ?

Answer and explanation

Correct answer: A. 0.25

  1. Step 1: The probabilities of all outcomes add up to .
  2. Step 2: , so .
Answer
0.25.
Why not the others: 0.75: This is the probability of red or blue, not green. 0.05: This subtracts and from instead of . 1.15: This adds all three numbers to instead of subtracting the two known from .

Practise more Statistics and Probability.

Free questions with an explanation for every one, and full timed GCSE English and Maths Resits (Grade 4) mock tests.