I got this from a show, it’s pretty stupid…

Bob walks into a bar and asks the bartender for a glass of water. The bartender then takes out a gun and fires, barely missing Bob’s head. Bob then thanks and tips the bartender and walks out of the bar.

Why did Bob thank and tip him?

Two delivery boys, each working in different stores, are sent on errands to each other’s store. They start out at the same time, each walking at their own steady pace. They pass each other 7 minutes 15 second after they start out. They arrive at their destinations but turn around instantly to head back to [...]

You are in a lucky dip style competition. There is a bag with tickets in it. They are numbered 1 to 100. One of them wins tonight’s star prize, the others win nothing. It is equally likely that any one of the tickets is the winner. Only the host knows the lucky number. 100 people form a [...]

Andy, Bob, Charlie, and Dave are playing some cards. Dealer’s Choice.

When it’s Dave’s deal, he decides to play a game in which you are dealt 7 cards (out of a standard 52 card deck). The cards are dealt, and the player with the highest four-of-a-kind wins. If no one gets a four-of-a-kind, the cards are [...]

A document was independently checked for errors by two people. One of them found 32 errors, the other found 24 errors. It turned out that 8 of those errors were noticed by both people.

Estimate how many errors there actually were in the document.

On average, how many times do you need to flip a fair coin before you have seen a run of an odd number of heads, followed by a tail?

i.e. you only stop flipping when you have seen any of 1H1T or 3H1T or 5H1T or … all the way to infinity. e.g. HT, THT, HHHT, HHTTTHHHT are possible runs [...]

Here’s a problem posed by DP.

You have three die. You roll all three together (that counts as one roll). If you get any 6’s, you continue to roll with the remaining die/dice. You keep doing this until all three die show a 6.

What is the mean number of rolls you’d make to get all three [...]

1. I put a spore in a test tube. Every hour the spore divides into three parts, all the same size as the original part. If I put it in at 3 PM., at 9 PM. the tube will be completely full. At what time will the tube be one-third full?

2. Which is correct:

A: The Second Millennium [...]

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Tom
Two fair coins are tossed simultaneously until at least one of the two

shows a head. If only one of the two is a head, the other is tossed until

it turns up head. What is the expected number of tosses to get heads

on both the coins?

A well{known logical joke is a card saying on one side “The statement

on the other side is false” and on the other, “The statement on the

other side is true”. Clearly, it is impossible for either of the statements

to be true or false without leading to an inconsistency. However, if

both sides said “The statement on the [...]

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Logic