Question

A number is chosen at random from the first 100 positive integers. Find the probability that the number is divisible by 5. 1/10

Answer 1

The number of multiples of 5 from 1 to 100 is:

1≤5n≤100

1/5≤n≤20, since n must be an integer

1≤n≤20

So the multiples of five number 20-1+1=20 elements, and the probability of choosing one of the multiples from the first 100 positive integers is:

P(5n)=20/100=1/5