What is the probability that a randomly chosen number from 1 to 100 is not a multiple of 5
There are 20 numbers from 1 to 100 that are multiples of 5
So there are 80 which aren't, so
prob(not a multiple of 5 ) = ....
To calculate the probability that a randomly chosen number from 1 to 100 is not a multiple of 5, we need to determine the number of favorable outcomes (numbers that are not multiples of 5) and the total number of possible outcomes.
The favorable outcomes in this case are the numbers between 1 and 100 that are not multiples of 5. So we need to count the numbers from 1 to 100 that are not divisible evenly by 5.
To find the total number of favorable outcomes, we can subtract the number of multiples of 5 from the total number of outcomes.
The total number of outcomes is 100, as we are choosing a number from 1 to 100.
Now, let's calculate the number of multiples of 5 between 1 and 100. The first multiple of 5 in this range is 5, and the last multiple is 100. So the multiples of 5 can be written as: 5, 10, 15, ..., 100. We can observe that this is an arithmetic sequence with a common difference of 5. We can calculate the number of terms in this sequence using the formula:
n = (last term - first term)/common difference + 1
Applying this formula, we get:
n = (100 - 5)/5 + 1 = 20
Therefore, there are 20 multiples of 5 between 1 and 100.
To find the number of favorable outcomes (numbers that are not multiples of 5), we subtract the number of multiples of 5 from the total number of outcomes:
Number of favorable outcomes = Total number of outcomes - Number of multiples of 5
= 100 - 20
= 80
So, there are 80 numbers between 1 and 100 that are not multiples of 5.
Finally, we can calculate the probability by dividing the number of favorable outcomes by the total number of outcomes:
Probability = Number of favorable outcomes / Total number of outcomes
= 80 / 100
= 0.8 or 80%
Therefore, the probability that a randomly chosen number from 1 to 100 is not a multiple of 5 is 0.8 or 80%.