Question

80 individuals were entered in an online giveaway and each participant was given a corresponding number between 1 and 80. What is the probability that the random number generator will select a number that is not a multiple of 9?

Answer 1

Answer: 9/10 or 0.9

Explanation:

There are 8 multiples of 9 between 1 and 80, namely 9, 18, 27, 36, 45, 54, 63, and 72. Therefore, there are 80 - 8 = 72 numbers that are not multiples of 9.

The probability of selecting a number that is not a multiple of 9 is equal to the number of numbers that are not multiples of 9 divided by the total number of numbers. Therefore, the probability of selecting a number that is not a multiple of 9 is 9/10 or 0.9