Two students are inviting friends to a mutual party. Each student is inviting 5 of their 15 mutual friends, what is the probability that they will
invite the same 5 friends?
If you add the total amount of mutual friends between both of them, you have 30. Now both are inviting 5 totaling 10. We have 10 out of 30. Reducing it would give you 1/3 probability.