Probability of fake accounts

Question

I came across the following question which is simple, but the wording is confusing:

In a network, 5% of users are fake. Also, fake users send friend request 10 times more than real users. What is the probability of a random friend request being fake?

I thought that following:

P(F)=0.05

P(R|F)=10(1-p(R|F)) so P(R|F)=10/11 and P(R|~F)=1/11

Now should I solve for P(F|R)?



Thanks!

Answer 1