Question

N is a 3 digit number that is multiple of 7, what is the probability that it will be a multiple of 5

Answer 1

Answer:

Using the Principal of Exclusion-Inclusion,

If it's given that the number is a multiple of 7,it needs to be a multiple of 35 if the same number is also a multiple of 5.

There are about [900/35]= 25 numbers satisfying this condition.

And the sample space here, are the collection of three digit numbers divisible by 7 which is [900/7]= 128.

Therefore the probability of the given event= 25/128