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Puzzles and Brain Teasers
Brain teasers and puzzles help you to train your brain. So go ahead, take our Brain Teaser. And don't take a peek at the answer until you have tried really hard.Brain Teasers and Puzzles
Introducing a lady to her friend, Juliet said, "Her father-in-law's father's only son's, only daughter's brother, is grandfather to my daughter." How is the woman related to Juliet?
Note: My daughter's father's grandfather had only one son and one daughter.
Answer 
The lady is Juliet's mother-in-law.
You have two vessels. One has a capacity of 8 gallons and the other of 3 gallons. How do you use them to get exactly 7 gallons of water?
Note - You cannot estimate by pouring out a random amount of water from or into any of the vessels. Also you cannot use any other vessel (s) besides these two, nor are you allowed to make any marking(s) on the vessels.
Answer
| Operation | 8 gallon vessel (Vessel P) | 3 gallon vessel (Vessel Q) |
|---|---|---|
| Initially | 0 | 0 |
| Fill P | 8 | 0 |
| Take out 3G from P into Q, by filling Q to the brim | 5 | 3 |
| Empty Q | 5 | 0 |
| Again, take out 3G from P into Q, by filling Q to the brim | 2 | 3 |
| Empty Q | 2 | 0 |
| Pour remaining 2G from P into Q | 0 | 2 |
| Fill P | 8 | 2 |
| Fill Q up to brim by pouring out water from P and 7G will remain in Q | 7 | 3 |
At what time will the hands of a clock (the minute hand and the hour hand) come together after 3:00 pm?
Answer
16 4/11 mins past 3:00pm.
At 3:00pm, the minute and hour hand are distanced by a space of 15mins. In order to meet, the minute hand has to gain 15mins over the hour hand.
Thus, the minute hand gains 55 mins over the hour hand in 60 mins.
The minute hand gains 15 mins over the hour hand in (60/55) * 15 mins = 16 4/11
Thus after 3:00pm the minute and hour hands will meet at 16 4/11 mins past 3.
In an interview for a Business school entrance exam the interviewer told the candidate "You have the option to choose between one tough question and 20 easy ones. Make your pick." Ben smartly answered, "I would go for the tough one." On his response the examiner asked him "What came first -- the hen or the egg?" Ben was nonplussed for a moment, but after a while firmly replied "The egg". On this the examiner with piqued interest asked "Why so?"
Can you tell us Ben's reply, as his answer impressed the examiner and he was selected for admission to that Business school?
Answer
Ben's reply to the examiner was "The deal was just for one tough question!"
In an 800 m marathon, Steve managed to overtake his friend, Roderick, in the last 7 seconds of the race, who would have otherwise finished second.
- What place did Steve achieve after overtaking his friend?
- What place would Steve have achieved had he managed to overtake the last runner?
Answer
- Steve stood second by overtaking the second runner and not first which is a common mistake made by most of us.
- How can one overtake the last runner?
A train is scheduled from Amsterdam to New York (say Train A) and another from New York to Amsterdam (say Train B). The distance between the two stations is 3500 miles. At 14:00 hrs Train A leaves Amsterdam at a constant speed of 50 miles/hr. Two hrs later Train B leaves New York at a constant speed of 80 miles/hr. Each train makes a halt for 20 min at a station 20 miles from its starting point. Which train is nearer to New York when they meet?
Answer
Both the trains are equidistant from New York at the meeting point. The distance of the meeting point from New York will obviously be the same for both trains.
Nancy likes fresh flowers. Hence her husband got her some flowers. She found that if she put one flower per vase in her house, she had one flower left. But if she put two flowers per vase, she had one vase empty. How many flowers and vases did Nancy have?
Answer
Nancy had 4 flowers and 3 vases.
Let x be the number of flowers, and y be the number of vases.
x - y = 1
or
y = x - 1
From the statement "if she put two flowers per vase, she had one vase empty", we get:
2 (y - 1) = x
or
2 (x - 1 - 1) = x (putting the value of y from equation 1)
or
2x - 2 - 2 = x
or
2x - x = 4
or
x = 4
Hence, y = 3
Thus, Nancy had 4 flowers and 3 vases.
You are in a summer camp. As part of a team event you have to reach the top of the tree house at night and send a signal to your teammates. On reaching the tree top you find there a match, kerosene lamp, an oil burner, and a wood burning stove. Which would you light first?
Answer
The match.
Without lighting the match you cannot light any of the others.
It's Christmas time. Rachel has to decorate the Christmas tree with colorful lights. Her husband had packed these away in boxes last Christmas. One box has red lights, one box has blue, and one box has both red and blue. However, in the hurry to pack, her husband had labeled all the boxes wrongly. How can Rachel find out what each box contains by drawing just one light from one box?
Answer
Rachel takes one light out from the box which is labeled 'Blue and Red'. If it is a blue light, then this is the box which contains only blue lights, since the only other box that can contain blue lights is the one which has both blue and red lights. However, this cannot be that box since it already had the label 'Blue and Red' which we know is incorrect.
This means that the box marked 'Blue' actually contains red balls. This is because the only other box that remains is already marked 'Red' which we know is incorrect. This also means that the box marked 'Red' would contain both blue and red balls.
Had Rachel picked out a red light from the first box, then similar reasoning would lead us to the correct results.
Mrs. Benette was a school teacher who noticed that she took the same time to go to school in the morning as she took on her return journey from school back home, in the evening. One day she happened to discover something.
When she left home, the hour hand and the minute hand were cast exactly opposite each other and on reaching school she found them to be together.
Similarly, when she quit school in the evening, the hour hand and the minute hand were together and the moment she arrived home, they were exactly opposite each other.
How much time did Mrs. Benette spend traveling? Give the minimal possible answer.
Answer
1 hr, 5 mins and 27.2 secs.
The minute hand and the hour hand are together 11 times, in twelve hours,. It means that after every 12/11 hours, both the hands are together.
Similarly, the minute hand and the hour hand are exactly opposite to each other 11 times, in twelve hours. It means that after every 12/11 hours, both the hands are opposite each other.We know that at 12:00 both the hands are together and at 6:00 both the hands are exactly opposite to each other.
After 6:00, both the hands are in opposition at [6+(12/11)] hours, [6+2*(12/11)] hours, [6+3*(12/11)] hours and so on. The sixth such time is [6+6*(12/11)] hours, which is the first time after 12:00. Thus after 12:00, both the hands are opposite to each other at 12:32:43.6.
Hence, Mrs. Benette takes 32 minutes and 43.6 seconds to reach home from school. Her total travel time is twice of this time, which equals to 1hr, 5mins and 27.2 secs.
A wildlife photographer along with his driver was moving through an African jungle in his jeep. The jungle was dense and the road bumpy. The jeep accidentally hit a rock and the two men were thrown from their seats. The photographer's digital watch fell from his breast pocket and its battery popped out. Neither of them knew the correct time to re-synchronize the watch.
Thus the photographer asked his driver to visit the nearest forest officer's home and inquire the time. The driver drove the jeep at a constant speed to the forest officer's place, asked him the time, rested there for 5 mins and drove back to the jungle at the same speed at which he had gone. On the driver's arrival the photographer could set the right time on his watch. Can you tell me how?
Note - The driver did not have his own watch and neither did the forest office have a spare one which he could lend to the driver to take back with him.
Answer
Assume that when the driver left, the photographer had tuned his watch to a random time of 12:00 hrs.
Let the total travel time of the driver be 2t, as he drove with the same speed on his forward and backward journey.
On the driver's return, the photographer's watch read (12 + 5/60 + 2t). From this he could find out the value of t. The driver's journey from the time he quit the forest officer's home was T+t ( T being the time the driver noted while setting back for the jungle from the forest officer.) Since both the quantities are known the correct time could be determined.