Question

Using a sixteen-sided number cube, what is the probability that you will roll an even number or an odd prime number? The number 1 isn't an odd prime. Round to three decimals.

Answer 1

1. Let a: rolling an even number, b: rolling an odd prime number

2. a={2, 4, 6, 8, 10, 12, 14, 16}, b={3, 5, 7, 11, 13}

3. So n(a)=8, n(b)=5 , n(Sample Space)=n(S)=16

4. Since a and b are mutually exclusive events, that means they have no common elements, P(a or b)=P(a)+P(b)=$\frac{n(a)}{n(S)}+ \frac{n(b)}{n(S)}= \frac{8}{16}+ \frac{5}{16}= \frac{13}{16}= 0.813$