Book Of Ha Ha 3

Coin Flip

One day, Bob came home from school and proudly told his father, "My teacher taught us about the probability of a coin flip today! A coin will land on heads 50% of the time all the time!"

Bob's father: That's... not quite how it works.

Bob: Nuh-uh! My teacher said so!

Bob's father: Well the educational system is garbage.

Bob: Huh?

Bob's father: Nothing.

Seeing a lesson that needed to be taught, Bob's father pulled out a coin and told his son, "Alright son, I bet you that this coin will land on heads. If you win, I'll buy you ice cream. If I win, you'll have to do the chores for the rest of the day."

Bob: Deal.

Bob's father casually flips the coin and it lands on heads.

Bob: How could this happen?

Bob's father: Because it's a small sample size. It doesn't reflect the actual probability.

Bob: Let's try again, It has to even out by landing on tails next time!

Bob's father: Let's raise the stakes this time. I'll flip the coin three times. If it lands on tails for any of them, you win and I'll buy you a tub of ice cream. If it lands on heads for all of them, you'll have to do the chores for the rest of the week.

Bob: Ok.

Bob's father flips the coin again and to Bob's amazement it lands on heads each time.

Bob: That can't be right! Why did this happen?

Bob's father: Because it's an outlier. It doesn't usually happen, but it'll show up from time to time across large data sets.

Bob: That makes sense. I bet it'll land on tails a lot in the next few flips.

Bob's father: You still don't get it. That's the gambler's fallacy. I'll flip the coin five more times. If you win, I'll buy you Half-Life 3. If I win, you'll have to do the chores for the rest of the month.

Bob: Fine.

Amazingly, all five coin flips resulted in heads.

Bob: That's impossible! How could this happen?

Bob's father: Because this is a miracle! The chances of this happening are about the chances your mom and I's marriage would have worked out.

Bob: That's not why she left.

Bob's father: Truth is stranger than fiction.

Bob: I don't believe this. It has to land on tails eventually.

Bob's father: The lesson doesn't seem to be sinking in. Let's go big. I'll flip the coin seven more times. If you win, I'll buy you anything you want. If I win, you'll have to do the chores until you go to college.

Bob hesitates for a moment in deep contemplation before finally nodding in agreement.

With each subsequent flip landing on heads, the life in Bob's eyes died a little. When the final flip landed on heads, a single tear rolled down Bob's cheek.

Bob: Why, dad? Why?

Bob's father: Because this is a two-headed coin.