Question

A school contest has every student pick 4 different numbers from 1-10. If you pick the correct 4 numbers, you get a day off of school. What is your probability of winning?

Answer 1

`1/210~~0.00476`

Explanation:

We're picking 4 numbers without regard to the order in which we're picking - so it's a combination question.

`C_(n,k)=((n),(k))=(n!)/((k!)(n-k)!)` with `n="population", k="picks"`

There are `((10),(4))=210` different combinations possible and only 1 of which will get you a day off from school. So the probability of picking it is:

`1/210~~0.00476`