Here is a problem I am having difficulty with. I think it should be simple but I cannot find the solution online.

Given that 25% of families have a fish tank, John asked 40 of his friends and only 10% of them had a fish tank. What is the p value?

I am guessing the question is what is the probability of having 4 (or fewer) families having a fish tank out of a sample of 40 families.

Tanks in advance