# Lying monkey

From Math Puzzle Wiki

You are a contestant on the hit game show "Lying Monkey." You are shown a hat which contains 80 folded $1 bills and 20 folded $5 bills. The trained talking monkey reaches in to the hat and pulls out a folded bill, but you cannot see whether it is a 1 or a 5. The monkey tells you that the bill is a 1, but from watching the show, you know that the monkey lies 30% of the time. What is the probability that the monkey is actually holding a $5 bill?