A lottery game has balls numbered 1 through 21. What is the probability of selecting an even numbered ball or a 9?
To find the probability of selecting an even numbered ball or a 9, we need to calculate the sum of the probabilities of these two events.
First, let's find the probability of selecting an even numbered ball. There are 10 even numbers from 1 to 21 (2, 4, 6, 8, 10, 12, 14, 16, 18, and 20) out of a total of 21 balls. Therefore, the probability of selecting an even numbered ball is 10/21.
Next, let's find the probability of selecting a 9. There is only one ball numbered 9 out of a total of 21 balls. Therefore, the probability of selecting a 9 is 1/21.
Finally, we need to find the sum of these probabilities. Therefore, the probability of selecting an even numbered ball or a 9 is (10/21) + (1/21) = 11/21.
So, the probability of selecting an even numbered ball or a 9 is 11/21.