choose a number 1 to 100. What is the probability that the number is not a multiple of 5?
First you have to determine how many multiples of 5 there are between 1 and 100.
5, 10 , 15, 20 , 25... etc.
subtract that number from 100 and that will give you how many are not multiples of 5.
Put that answer/100 to get the probability.
0.86
To find the probability that a number chosen from 1 to 100 is not a multiple of 5, we first need to determine the total number of numbers in that range that are not multiples of 5.
There are two main ways to approach this problem:
1. Counting method:
- Count the total numbers from 1 to 100 that are multiples of 5, which is 100 ÷ 5 = 20.
- Subtract this count from the total count of numbers from 1 to 100, which is 100.
- Therefore, there are 100 - 20 = 80 numbers that are not multiples of 5.
- The probability of choosing a number that is not a multiple of 5 is given by the count of favorable outcomes (80) divided by the count of all possible outcomes (100), so the probability is 80/100 = 0.8.
2. Formula method:
- The formula to find the probability is the count of favorable outcomes divided by the count of all possible outcomes.
- The favorable outcomes are the numbers in the range 1 to 100 that are not multiples of 5, which is 100 - 20 = 80.
- The total number of possible outcomes is 100.
- Therefore, the probability of choosing a number that is not a multiple of 5 is 80/100 = 0.8.
Both methods lead to the same answer: The probability that the number chosen is not a multiple of 5 is 0.8 or 80%.