Please help with this. Thanks.

Question

Addition and subtractionA spinner has the numbers 1 to 4 on it. The area given to each number relates to their chance of occurring.

1. The probability of spinning a number 4 is 0.1
2. The probability of spinning a number 1 is 0.5
3. The probability of spinning a number 2 is the same as spinning a number 3.
4. Calculate the probability of spinning a number 3.

Answer 1

Altogether these probabilities must add up to 1. so: 0.5 + 0.1 + 2*(probability of 3) = 1 . We can do that because probability of 2 and probability of 3 are the same.

therefore 2*(probability of 3) = 1 - 0.5 - 0.1 = 0.4 and probability of 3 is 0.4/2 = 0.2 .

so the probability of 3 is 0.2 or 1/5