The 100 Seat Airplane
People are waiting in line to board a 100-seat airplane. Steve is the first person in the line. He gets on the plane but suddenly can't remember what his seat number is, so he picks a seat at random. After that, each person who gets on the plane sits in their assigned seat if it's available, otherwise they will choose an open seat at random to sit in.
The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?
The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?
Hint: You don't need to use complex math to solve this riddle. Consider these two questions:
What happens if somebody sits in your seat?
What happens if somebody sits in Steve's assigned seat?
The correct answer is 1/2.
The chase that the first person in line takes your seat is equal to the chance that he takes his own seat. If he takes his own seat initially then you have a 100% chance of sitting in your seat, if he takes your seat you have a 0 percent chance. Now after the first person has picked a seat, the second person will enter the plan and, if the first person has sat in his seat, he will pick randomly, and again, the chance that he picks your seat is equal to the chance he picks someone your seat. The motion will continue until someone sits in the first persons seat, at this point the remaining people standing in line which each be able to sit in their own seats. Well how does that probability look in equation form? (2/100) * 50% + (98/100) * ( (2/98) * 50% + (96/98) * ( (2/96) * (50%) +... (2/2) * (50%) ) ) This expansion reduces to 1/2.
An easy way to see this is trying the problem with a 3 or 4 person scenario (pretend its a car). Both scenarios have probabilities of 1/2. Did you answer this riddle correctly?
YES NO
The chase that the first person in line takes your seat is equal to the chance that he takes his own seat. If he takes his own seat initially then you have a 100% chance of sitting in your seat, if he takes your seat you have a 0 percent chance. Now after the first person has picked a seat, the second person will enter the plan and, if the first person has sat in his seat, he will pick randomly, and again, the chance that he picks your seat is equal to the chance he picks someone your seat. The motion will continue until someone sits in the first persons seat, at this point the remaining people standing in line which each be able to sit in their own seats. Well how does that probability look in equation form? (2/100) * 50% + (98/100) * ( (2/98) * 50% + (96/98) * ( (2/96) * (50%) +... (2/2) * (50%) ) ) This expansion reduces to 1/2.
An easy way to see this is trying the problem with a 3 or 4 person scenario (pretend its a car). Both scenarios have probabilities of 1/2. Did you answer this riddle correctly?
YES NO
Add Up To 100 Riddle
With the numbers 123456789, make them add up to 100. They must stay in the same order. You can use addition, subtraction, multiplication, and division. Remember, they have to stay in the same order!
Hint:
Making An Apple Turnover
Hint:
Turning Water Into Ice Riddle
Hint:
100 Meter Sprint Riddle
Hint:
Turning Leaves Riddle
Hint:
100 Lawyers Riddle
Hint:
Turning Still Riddle
Hint:
Less Than 100 Riddle
Find a number less than 100 that is increased by one-fifth of its value when its digits are reversed.
Hint:
The Nosy Old Woman
My neighbors think I'm a nosy old woman, but today I witnessed a murder. I was looking out my window when I saw something through the window of the apartment building opposite me. A man was in the middle of murdering a woman. The strange thing was, after he finished strangling her, he turned around and our eyes met. It was eerie. Then he pointed at me and kept staring at me for a minute or two. All the time he was staring at me, his finger kept moving. I called the police a few minutes ago and they told me I will have to go down to the police station and give a statement tomorrow. I'm sure they will catch him. I saw his face very clearly.
What do you think the murderer was waving his finger at?
What do you think the murderer was waving his finger at?
Hint:
The murderer was counting the windows to see which floor the old woman was on. He is coming to kill her. Did you answer this riddle correctly?
YES NO
YES NO
The Robbery On The Third Floor Riddle
My wife and I took a much-needed holiday in England. It's a long flight from New York to London. We checked into a nice hotel. After a long day of sightseeing we just collapsed into bed. Just a few minutes ago, we were woken up by some noises outside. I looked out the window and the police were everywhere. They yelled up to me that there was a robbery and a murderer on the second floor. I'm on the third floor, and I can see and I can see that the cops have the stairs and elevators locked down. The murderer can't get up to our floor, so we're in no danger. My wife and I are tired, so we're going back to bed. I really hope they catch the guy.
Why did the police yell to the guy if he was on the 3rd floor?
Why did the police yell to the guy if he was on the 3rd floor?
Hint:
America and England have different ways of numbering floors. In America, it goes 1st floor, 2nd floor, 3rd floor. In England, it goes ground floor, 1st floor, 2nd floor. Did you answer this riddle correctly?
YES NO
YES NO
150 Pens Riddle
Rihanna brought home 150 pens but while packing them, she misplaced some of them. When her brother asked how many she had misplaced, she told him:
If you count in pairs, one will remain
If you count in a group of three, two will remain
If you count in a group of four, three will remain
If you count in a group of five, four will remain
If you count in a group of six, five will remain
If you count in a group of seven, nothing will remain.
How many pens do you think has she misplaced ?
If you count in pairs, one will remain
If you count in a group of three, two will remain
If you count in a group of four, three will remain
If you count in a group of five, four will remain
If you count in a group of six, five will remain
If you count in a group of seven, nothing will remain.
How many pens do you think has she misplaced ?
Hint:
100 Billion Neurons Riddle
Hint:
108 Spiders Riddle
Hint:
Ready For St. Patrick's Day
Hint:
Add Your Riddle Here
Have some tricky riddles of your own? Leave them below for our users to try and solve.