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
10 Boxes Riddle
There are ten boxes containing some balls. Each of the ball weighs exactly 10 grams. One of those boxes have defective balls (all the defective balls weigh 9 grams each).
An electronic weighing machine is provided to you and you are allowed only one chance of weighing on it.
How will you find out which box has defective balls ?
An electronic weighing machine is provided to you and you are allowed only one chance of weighing on it.
How will you find out which box has defective balls ?
Hint:
Let us simplify boxes by naming them from 1 to 10.
Now the trick here is to pick different number of balls from different boxes. So to simplify things, we will pick balls corresponding to box number.
Thus, pick 1 ball from Box 1, 2 balls from box 2, 3 balls from box 3 and so on. You will have 55 balls altogether. Now, put them all in the balance.
If all balls were weighing accurate 10 grams, the total weight of the 55 balls would have been 550 grams. But one of the box must have had the defective balls.
Suppose if the defective balls were in box number 2, then the total weight will be 2 grams less than 550. If the defective balls were in box 8, the total weight will be less than 8 grams from 550. In this way, you will be able to identify which box has the defective balls. Did you answer this riddle correctly?
YES NO
Now the trick here is to pick different number of balls from different boxes. So to simplify things, we will pick balls corresponding to box number.
Thus, pick 1 ball from Box 1, 2 balls from box 2, 3 balls from box 3 and so on. You will have 55 balls altogether. Now, put them all in the balance.
If all balls were weighing accurate 10 grams, the total weight of the 55 balls would have been 550 grams. But one of the box must have had the defective balls.
Suppose if the defective balls were in box number 2, then the total weight will be 2 grams less than 550. If the defective balls were in box 8, the total weight will be less than 8 grams from 550. In this way, you will be able to identify which box has the defective balls. Did you answer this riddle correctly?
YES NO
BDay Bash Riddle
I engaged in a strange activity. My birthday was approaching and I decided to collect money for my birthday bash. On the first day of the month, I kept a dollar in my piggy bank, on the second, I kept two dollars and on the third, I kept three and so on.
On my birthday, I had a total of 276 dollars in my piggy bank. Can you find out on which day of the month was my birthday?
On my birthday, I had a total of 276 dollars in my piggy bank. Can you find out on which day of the month was my birthday?
Hint:
23rd.
The easiest way to find out without engaging in any formula would be to simply add them:
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 + 20 + 21 + 22 + 23 = 276 Did you answer this riddle correctly?
YES NO
The easiest way to find out without engaging in any formula would be to simply add them:
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 + 20 + 21 + 22 + 23 = 276 Did you answer this riddle correctly?
YES NO
The Speed Of A Bee
Two bikes are traveling toward each other at a constant speed of 10 mph. When the bikes are 20 miles apart, a bee flies from the front wheel of one of the bikes toward the other bike at a constant speed of 25 mph. As soon as it reaches the front wheel of the other bike, it immediately turns around and flies at 25 mph toward the first bike. It continues this pattern until the two bikes smush the bee between the two front tires.
How far did the bee travel?
How far did the bee travel?
Hint:
25 miles.
The easiest way to think about this is to consider the time. The bikes will take 1 hour to touch, given that they start 20 miles apart and are each traveling toward each other at 10 mph.
Therefore the bee is buzzing back and forth at 25 mph for 1 hour. Did you answer this riddle correctly?
YES NO
The easiest way to think about this is to consider the time. The bikes will take 1 hour to touch, given that they start 20 miles apart and are each traveling toward each other at 10 mph.
Therefore the bee is buzzing back and forth at 25 mph for 1 hour. Did you answer this riddle correctly?
YES NO
Afternoon Bike Ride Riddle
Hester goes out for an afternoon bicycle ride. She rides for one hour at five miles an hour, then three hours at four miles an hour and finally two hours at seven miles an hour. How many miles did she ride in total?
Hint:
31 miles.
1 hour at 5 mph = 5 miles
3 hours at 4 mph = 12 miles
2 hours at 7 mph = 14 miles
5 + 12 + 14 = 31 miles Did you answer this riddle correctly?
YES NO
1 hour at 5 mph = 5 miles
3 hours at 4 mph = 12 miles
2 hours at 7 mph = 14 miles
5 + 12 + 14 = 31 miles Did you answer this riddle correctly?
YES NO
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