Question

A spinner has equal regions numbered 1 through 20. What is the probability that the spinner will stop on an odd number or a multiple of 5? Don't forget to reduce fraction.

Answer 1

Probability that the spinner will stop on an odd number or a multiple of 5 is 0.6

Explanation:

Probability =
`(Required outcomes)/(Total possible outcomes)`

We are given the equal regions numbered from 1 through 20 which means that our total possible outcomes are 20

Total possible outcomes: 20

Outcomes that spinner will stop on an odd number, n(Odd): 10

1, 3, 5, 7, 9, 11, 13, 15, 17, 19

Probability of spinner stoping on Odd number:

P(Odd) =
`(n(Odd))/(Total)` =
`(10)/(20)` =
`(1)/(2)` = 0.5

Outcomes that spinner will stop on a multiple of 5, n(5): 4

5, 10, 15, 20

Probability of spinner stoping on multiple of 5:

P(5) =
`(n(5))/(Total)` =
`(4)/(20)` =
`(1)/(5)` = 0.2

Odd numbers which are a multiple of 5 are: 5 and 15

So,

P(Odd and 5) =
`(2)/(20)=(1)/(10)=0.1`

Thus Probability of spinner stopping at odd number or a multiple of 5 becomes:

P(Odd or 5) = P(Odd) + P(5) - P(Odd and 5) = 0.5 + 0.2 - 0.1 = 0.6