An intelligent trader travels from one place to another with 3 sacks having 30 coconuts each. No sack can hold more than 30 coconuts. On the way, he passes 30 check points. At each check point, he has to give one coconut for every sack he is carrying. What is the maximum number of coconuts that he can have with him at the end of his journey?
He will have 25 coconuts with him at the end. The trick is to reduce the number of sacks as you pass checkpoints. The first 10 checkpoints require 3 coconuts each, which empties his first sack. The next 15 checkpoints require 2 coconuts each, which will empty his second stack. Now, he is left with 1 sack and 5 more checkpoints. So, the 5 checkpoints will take 1 coconut each. Therefore, he will be left with 25 coconuts.
A frog is at the bottom of a well. It is a 30 foot climb to get out. Each morning, the frog jumps 3 feet up the path out, but each night, as it sleeps, it slips back 2 feet down.
Thus, at the beginning of the first day, the frog has 30 feet to go, at the beginning of the second day it has 29 feet to go, and so on.
How many days does it take the frog to get out of the well?
It takes 28 days for the frog to get out (it gets out on the morning of the 28th day).
This is because on the beginning of the 28th day, the frog has 3 feet left to travel. Because the frog jumps 3 feet forward each morning, it will jump out of the well on this day.
A man was shot to death while in his car. There were no powder marks on his clothing which indicated that the gunman was outside the car. However, all the windows were up and the doors locked. After a close inspection was made, the only bullet holes discovered were on the man's body. How was he murdered?
A rich man's son was kidnapped. The ransom note told him to bring a valuable diamond to a phone booth in the middle of a public park. Plainclothes police officers surrounded the park, intending to follow the criminal or his messenger. The rich man arrived at the phone booth and followed instructions but the police were powerless to prevent the diamond from leaving the park and reaching the crafty villain. What did he do?
This is a true story from Taiwan. When the rich man reached the phone booth he found a carrier pigeon in a cage. It had a message attached telling the man to put the diamond in a small bag which was around the pigeon's neck and to release the bird. When the man did this the police were powerless to follow the bird as it returned across the city to its owner.
You have two sand hourglasses, one that measures exactly 4 minutes and one that measures exactly 7 minutes. You need to measure out exactly 2 minutes to boil an egg. Using only these two hourglasses, how can you measure out exactly 2 minutes to boil your egg?
Flip over both hourglasses at the same time.
1. After 4 minutes, the 4-minute hourglass will be done, and there will be 3 minutes left in the 7-minute hourglass. Immediately flip the 4-minute hourglass over again.
2. After 3 more minutes, the 7-minute hourglass will be done, and there will be exactly 1 minute left in the 4-minute hourglass. Immediately flip the 7-minute hourglass over again.
3. After 1 more minute, the 4-minute hourglass will be done again, and there will be exactly 6 minutes left in the 7-minute hourglass. Immediately flip over the 4-minute hourglass.
4. After 4 more minutes, the 4-minute hourglass will be done again, and there will be exactly 2 minutes left in the 7-minute hourglass. At this point, put your egg in the boiling water. When the 7-minute hourglass is done, it will have been exactly 2 more minutes, and your egg will have boiled just right.
Or after step 2 just flip 7-minute hourglass for second minute.