Question

A sixteen-sided number cube has the numbers 1 through 16 on each face. Each face is equally likely to show after a roll. What is the probability that you will roll an even number or an odd prime number? Round to the nearest thousandth.

A 0.875

B 0.219

C 0.063

D 0.813

Answer 1

There are 8 faces with even numbers. (2, 4, ..., 16)

There are 5 odd primes between 1 and 16. (3, 5, 7, 11, 13)

There is no common element between the two lists, so the events are disjoint. Therefore


`\mathbb P(\text{even OR odd prime})=\mathbb P(\text{even})+\mathbb P(\text{odd prime})=\frac8{16}+\frac5{16}=(13)/(16)\approx0.813`