Mind Teasers :
Crossing The River In Minimum Time Puzzle
Four people need to cross a dark river at night.
* They have only one torch and the river is too risky to cross without the torch.
* If all people cross simultaneously then torch light wont be sufficient.
* Speed of each person of crossing the river is different.cross time for each person is 1 min, 2 minutes, 7 minutes and 10 minutes.
What is the shortest time needed for all four of them to cross the river ?
The initial solution most people will think of is to use the fastest person as an usher to guide everyone across. How long would that take? 10 + 1 + 7 + 1 + 2 = 21 minutes. Is that it? No. That would make this question too simple even as a warm up question.
Let's brainstorm a little further. To reduce the amount of time, we should find a way for 10 and 7 to go together. If they cross together, then we need one of them to come back to get the others. That would not be ideal. How do we get around that? Maybe we can have 1 waiting on the other side to bring the torch back. Ahaa, we are getting closer. The fastest way to get 1 across and be back is to use 2 to usher 1 across. So let's put all this together.
1 and 2 go cross
2 comes back
7 and 10 go across
1 comes back
1 and 2 go across (done)
A strange tradition is followed in an orthodox and undeveloped village. The chief of the village collects taxes from all the males of the village yearly. But it is the method of taking taxes that is interesting.
The taxes paid in the form of grains and every male should pay equal pounds corresponding to his age. In simpler terms, a man aged 10 years will have to pay 10 pounds of grains and a 20 years old will be paying 20 pounds of grain.
The chief stands on a riser containing 7 different weights next to a large 2 pan scale. As per the interesting custom, the chief can only weigh using three of the seven weights.
In such a scenario, can you calculate what must be the weights of the seven weights each and who is the oldest man the chief can measure using those weights?
In a contest, four fruits (an apple, a banana, an orange, and a pear) have been placed in four closed boxes (one fruit per box). People may guess which fruit is in which box. 123 people participate in the contest. When the boxes are opened, it turns out that 43 people have guessed none of the fruits correctly, 39 people have guessed one fruit correctly, and 31 people have guessed two fruits correctly.
How many people have guessed three fruits correctly, and how many people have guessed four fruits correctly
It is not possible to guess only three fruits correctly: the fourth fruit is then correct too! So nobody has guessed three fruits correctly and 123-43-39-31 = 10 people have guessed four fruits correctly.
Three men are living in a desert namely – Alex, Brian and Chris.
Alex hates Chris and thus he decides to kill him. To succeed in his evil intentions, he poison the water supply of Chris. Since they are living in desert, he will have to drink water or he will die of thirst.
Brian is not aware of the actions of Alex and he plans to kill Chris as well. To do this, he killed the water supply of Chris.
This is more of a philosophical question than being a riddle or a puzzle. The action of Brian directly led to the result which is the death of Chris. Thus he murdered Chris. In a sense, Chris died due to the lack of water. It is the circumstances that ultimately led to his death.
An old man in the village feels that his end is near. He calls his two sons to discuss about the land he owns and other properties. He tells them to have a race on their horses till the city border. The one with the slower horse will be rewarded with the entire property.
Both of them keep wandering here or there without any result as no one is filling to reach the border. Then they visit the wise man of the village and seek his advice. The wise men tells them something listening to which they jump on the horses and race as fast as they can till the city border.
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?
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.
On a random day , i was not able to logged-in with my bank password , so i contacted them on phone.
Our conversation is stated as :
myself : My password is altered.
myself : I am not able to logged-in.
customer-executive : Your password is distinct this time and it got 8 letters , out of which 2 are same of your previous password.
myself: Thanks , now i am able to logged-in.
Although it looks complicated, the answer is simple. The password to his computer is JIGSAW.
1st letter of Jug = J
2nd letter of Birthdays = I
3rd letter of Fights = G
4th letter of Cars =S
2nd letter of Laptops = A
1st letter of Watch = W
100 people are standing in a circle. The person standing at number 1 is having a sword. He kills the person next to him with the sword and then gives the sword to the third person. This process is carried out till there is just one person left.
Till the number is the power of 2, the last person to survive will be the one who started it. But since the number here is not the power of 2, we will take the greatest power of 2 that is less than the number which is 64.
100 - 64 = 36
36 people are killed as 2, 4, 6, ..., 72. Thus the sword will now be given to the 73rd person. Now he is the first person to start in the remaining 64 people. Thus he will be the one to survive.
Angelina Jolie is trapped in a tomb. The only way to escape is figure out a 13 character password. Following are the five clues that are available to her.
Precisely two of the below statements are false.
The password is confined within this sentence.
The password is not in this hint.
The password is inside only one of these statements.
At least one of the above statement is a lie.