3 Envelops Riddle
You are sitting in front of your interviewer. He gives you three envelopes. One of them contains an offer letter and the other two are empty. You pick up one of them. Now, the interviewer opens up one of the envelope lying on the table and you find out that it is blank.
Now, he gives you a chance to switch your envelope with the one on the table. Would you switch it? Why or why not?
Now, he gives you a chance to switch your envelope with the one on the table. Would you switch it? Why or why not?
Hint:
Yes, you should switch the envelope. In the beginning when you picked up the envelope, you had a 1/3 probability of finding an offer letter in the envelope. There was 2/3 chance that the letter was there in the two envelopes on the table.
If you keep your selected envelope, you still have a 1/3 chance of finding an offer letter in that. However, since the interviewer has removed one empty envelope from the table, if you switch, you have a probability of 2/3 that the offer letter is inside that. Did you answer this riddle correctly?
YES NO
If you keep your selected envelope, you still have a 1/3 chance of finding an offer letter in that. However, since the interviewer has removed one empty envelope from the table, if you switch, you have a probability of 2/3 that the offer letter is inside that. Did you answer this riddle correctly?
YES NO
Hosting A Game Show Riddle
The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).
Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.
You cannot hear the goats from behind the doors, or in any way know which door has the prize.
Should you stay, or switch, or doesn't it matter ?
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).
Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.
You cannot hear the goats from behind the doors, or in any way know which door has the prize.
Should you stay, or switch, or doesn't it matter ?
Hint:
You better switch!
Your first choice has a 1/3 chance of having the car, and that does not change. The other two doors HAD a combined chance of 2/3, but now a Goat has been revealed behind one, all the 2/3 chance is with the other door. Did you answer this riddle correctly?
YES NO
Your first choice has a 1/3 chance of having the car, and that does not change. The other two doors HAD a combined chance of 2/3, but now a Goat has been revealed behind one, all the 2/3 chance is with the other door. Did you answer this riddle correctly?
YES NO
3 Pills Riddle
If a doctor gives you 3 pills and tells you to take one pill every half hour, how long would it take before all the pills had been taken?
Hint:
1 hour! Take the 1st pill right away, half an hour later take the 2nd and half an hour after that the 3rd. Total time spent: 1 hour! Did you answer this riddle correctly?
YES NO
YES NO
The Forgetful Camping Trip
You go camping and realize you forgot your sleeping bag. You get it come back and then realize you forgot your flashlight. You go and get it, but when you come back you find your sleeping bag is missing. You then find out you forgot your tent. When you go back and get it you see your sleeping bag, get it and leave your tent. You go back to the camp site remembering you left your tent at home. You also come to see your flashlight is now missing. You get your tent and see your flashlight, you get that too. You then see your sleeping bag is gone. You are so exhausted you leave it at home. Why does every thing keep going missing?
Hint:
You bring your sleeping bag home when you realize you forgot your flashlight. You leave your sleeping bag at home. You realize you did not bring your tent, go home with you flashlight. Instead of picking up your tent you see your sleeping bag and take that instead leaving your tent and flashlight at home. You go back when you get to camp because you now need your flashlight and tent. You bring your sleeping bag. And when you get your tent and flashlight you leave your sleeping bag. Every time you bring something to the camp site you leave what you had there at home. Did you answer this riddle correctly?
YES NO
YES NO
Little Johnny's Cats Riddle
Little Johnny's teacher asks him, "If I gave you two cats, then two more, and two more cats; how many would you have?"
Little Johnny replies, "Seven!"
His teacher asks him again more slowly, "If I gave you two cats, then two more, and two more cats; how many would you have?"
But again Little Johnny replies, "Seven!"
Next she asks, "If I get two cats, then two more, and two more cats; how many would I have?"
Little Johnny replies, "Six!"
"Good Job Johnny! Now if I gave you two cats, then two more, and two more cats; how many would you have?"
Johnny thinks for a second, "Seven."
But Johnny is not wrong. Why?
Little Johnny replies, "Seven!"
His teacher asks him again more slowly, "If I gave you two cats, then two more, and two more cats; how many would you have?"
But again Little Johnny replies, "Seven!"
Next she asks, "If I get two cats, then two more, and two more cats; how many would I have?"
Little Johnny replies, "Six!"
"Good Job Johnny! Now if I gave you two cats, then two more, and two more cats; how many would you have?"
Johnny thinks for a second, "Seven."
But Johnny is not wrong. Why?
Hint:
A Time To Travel Riddle
Hint:
3 Apples Riddle
Hint:
Doorway To Heaven
You die then you find yourself in limbo, and you see two doors. One of them leads you to hell and the other one heaven. They are being guarded by two guardians. The guardian guarding the doorway to heaven always tells the truth and the guardian guarding the doorway to hell always lies. What is the one question you will ask to either of the guardians to find out which door will lead you to heaven?
Hint:
If I asked the other guardian which door leads to heaven, what would he tell me? Did you answer this riddle correctly?
YES NO
YES NO
Left Behind Riddle
Hint:
Losing A New York Bet
You are hanging around in NYC when a person approaches you.
"Leaving the bald people aside, I can bet a hundred bucks that there are two people living in NYC who have same number of hairs on their heads," he says to you.
You say that you will take the bet. After talking to the man for a couple of minutes, you realize that you have lost the bet.
What did the person say to you that proved his statement ?
"Leaving the bald people aside, I can bet a hundred bucks that there are two people living in NYC who have same number of hairs on their heads," he says to you.
You say that you will take the bet. After talking to the man for a couple of minutes, you realize that you have lost the bet.
What did the person say to you that proved his statement ?
Hint:
This problem can be best solved using the pigeonhole principle.
The argument will go like this:
Assume that all the non-bald people in NYC have different number of hairs on their head. The population is about 9 million and let us assume that there are 8 million among them who are not bald.
Now, those 8 million people need to have different number of hairs. On an average, people have just 100, 000 hairs on their head. If we keep on assuming that there is someone with just one hair, someone with two, someone with three and so on, there will be 7, 900, 00 other people left who will have more than 100, 000 hairs on their head and need different number of hairs.
Now, as per this assumption, if we keep increasing one hair for each person, to make everybody hair different in numbers, we will come across someone with 8, 000, 000 hairs. But that is practically impossible (even 1, 000, 000 is impossible). Thus there must be two people who are having same number of hairs. Did you answer this riddle correctly?
YES NO
The argument will go like this:
Assume that all the non-bald people in NYC have different number of hairs on their head. The population is about 9 million and let us assume that there are 8 million among them who are not bald.
Now, those 8 million people need to have different number of hairs. On an average, people have just 100, 000 hairs on their head. If we keep on assuming that there is someone with just one hair, someone with two, someone with three and so on, there will be 7, 900, 00 other people left who will have more than 100, 000 hairs on their head and need different number of hairs.
Now, as per this assumption, if we keep increasing one hair for each person, to make everybody hair different in numbers, we will come across someone with 8, 000, 000 hairs. But that is practically impossible (even 1, 000, 000 is impossible). Thus there must be two people who are having same number of hairs. Did you answer this riddle correctly?
YES NO
The Lay Of The Land Riddle
This shows you the lay of the land
So you know where things can be found
Many of them also show roads
So you know how to get around
So you know where things can be found
Many of them also show roads
So you know how to get around
Hint:
Straight After Lightning Riddle
When its really stormy outside
This is something you hear
It happens straight after lightning
When it is very near
This is something you hear
It happens straight after lightning
When it is very near
Hint:
Lying Lawyers Riddle
Hint:
Napping During A Race
Hint:
Pills A And B Riddle
You have two bottles of pills marked with the label A and B. The pills are identical. The doctor has asked you to take one A pill and one B pill daily. You cant take more or less than that.
While taking out the pills one day, you took out one pill from A and by mistake took out two from B. You have no idea which pill is which now.
You cant throw away the expensive pills. What will you do now?
While taking out the pills one day, you took out one pill from A and by mistake took out two from B. You have no idea which pill is which now.
You cant throw away the expensive pills. What will you do now?
Hint:
Cut each of the three pills in half and put each half in two piles. Now, each of the two piles will contain half of pill A and two halves of pill B.
Take one pill A and cut into half and put the two halves in the two piles. Now, each pile will have two halves of pill A and two halves of pill B which means one pill A and one pill B. You can take one pile today and one pile the next day. Did you answer this riddle correctly?
YES NO
Take one pill A and cut into half and put the two halves in the two piles. Now, each pile will have two halves of pill A and two halves of pill B which means one pill A and one pill B. You can take one pile today and one pile the next day. Did you answer this riddle correctly?
YES NO
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