Question

Using a sixteen-sided number cube, what is the probability that you will roll an odd number or an even prime number? Round to three decimals.

a. 0.813
b. 0.313
c. 0.563
d. 0.156

Answer 1

0.563

Explanation:

Probability is defined by the amount of desirable outcomes over the total number of outcomes. When rolling a 16 sided number cube, there are 16 different numbers you can roll, which means 16 total outcomes. There are 8 odd numbers that you can possibly roll:

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

Now, an even prime numbers are included in the desirable outcomes too. The only even prime number is 2. Since the odd numbers and even prime numbers do not have common term, to get the total desirable outcomes, you can add the two: 8 + 1 = 9. From the basic probability formula you can say the probability is 9/16 or 0.5625. This rounds to 0.563.

If you were too lazy to calculate, you can realize that 0.563 is the only reasonable answer because it is close to 1/2 or 0.5 and half the numbers are odd and only one is even and prime which makes the amount a bit over 1/2.