Question

events with no outcomes in common are called disjoint events or mutually exclusive events. To find the probability of mutually exclusive events, add the probabilities of the individual events. Suppose you select a number from 21 to 30 at random. What is the probability of selecting a number that is even or prime?

Answer 1

We are selecting a number from 21-30 at random.

There are 5 even numbers (22, 24, 26, 28, 30) and 2 prime numbers (23, 29) within this group of numbers.

The probability of selecting a number that is even OR prime means that we can add the probability of selecting an even number and the probability of selecting a prime number together.

There are 10 numbers in total from 21-30, including 21.

The probability of selecting an even number is:

P(even number) = 5/10 = .5

The probability of selecting a prime number is:

P(prime number) = 2/10 = .2

Now, let's add these probabilities together:

P(even number) + P(prime number) = .5 + .2 = .7

Therefore, the probability of selecting a number that is even or prime is .7.