Brainteaser Puzzles, Mind Teaser with Math Logic

The Expedition (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Fri, 12 Oct 2007 03:07:00 +0000

An expedition to explore the Lurgi desert is about to set off. It consists of four men and each one has enough food to last him five days. After some distance, one man gets sick and has to turn back. He takes with him just enough food to last him till he gets back to base. Then the second man does the same, and the third. How many day’s journey was the last man able to make into the desert and get back safely? (You must assume that the men only travel in units of one day and that they can give food to the others.)

Again, in order to make it more interesting, I am not giving the answer or the clue straight. Please try to give your answer in the comment box at my blog or by yahoo groups email, I’ll check it out as soon as possible, and I’ll give the clue and the answer eventually. Thx guys!!

Chess Player (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Fri, 12 Oct 2007 03:05:00 +0000

Two men played five games of chess. They each won the same number of games. How was this possible?

The murder (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Tue, 09 Oct 2007 17:19:00 +0000

This is the hardest question so far, please try to solve it!!

One evening there was a murder in the home of married couple, their son and daughter. One of these four people murdered one of the others. One of the members of the family witnessed the crime.

The other one helped the murderer.

These are the things we know for sure:

1. The witness and the one who helped the murderer were not of the same sex.

2. The oldest person and the witness were not of the same sex.

3. The youngest person and the victim were not of the same sex.

4. The one who helped the murderer was older than the victim.

5. The father was the oldest member of the family.

6. The murderer was not the youngest member of the family.

Who was the murderer?

Clue:

Establish what we know about the youngest person first. This person cannot have been either the victim three, the helper four or the killer five. Then work out who was oldest, youngest, etc. After this draw up the various possibilities about who could have been what.

Answer:

We know from (3) that the youngest person was not the victim, from (4) that the youngest person was not the helper and from (6) that the youngest person was not the killer. The youngest person can only have been the witness therefore. If we make up a chart there are now three possible combinations:

Oldest person (father) H H M

Next to oldest (mother) V M H

Next to youngest (son) M V V

Youngest (daughter) W W W

(H = Helper ; V = Victim ; M = Murderer ; W = Witness)

We can work out from (5) that the father was the oldest, from (2) that the youngest person must have been the daughter. Therefore the next to the youngest must have been the son and the next to the oldest, the mother.

Of three possibilities: the first is impossible (from (3) – the youngest person and the victim were of different sexes); the third is also impossible (from (1) – the witness and the helper were of different sexes). Therefore only the second possibility holds – and the mother was the murderess.

The Kidnappers (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Tue, 09 Oct 2007 17:17:00 +0000

When the Rajah’s daughter was kidnapped, he arrested three young men. The suspects were brought before his wise old guru.

Ravi said: ‘Gopal did it.’

Gopal said: ‘But that’s not true.’

Kushwant said: ‘It was Ravi who did it.’

Ravi said: ‘What Kushwant says next will be true.’

Gopal said: ‘What Ravi has just said is false.’

Kushwant said: ‘Ravi has made two false statements.’

The guru meditated for a few minutes before whispering the name of the guilty person in the Rajah’s ear. Which name?

Again, in order to make it more interesting, I am not giving the answer or the clue straight. Please try to give your answer in the comment box at my blog or by email, I’ll check it out as soon as possible, and I’ll give the clue and the answer eventually. Thx guys!!

Surprising Memory (Just Playing Around)

noreply@blogger.com (Andri) — Sun, 07 Oct 2007 17:07:00 +0000

An easy way to surprise your friends will be for you to memorize the following calculations:

1x9+2=11

12x9+3=111

123x9+4=1111

1234x9+5=11111

12345x9+6=111111

123456x9+7=1111111

1234567x9+8=11111111

12345678x9+9=111111111

Or:

9x9+7=88

98x9+6=888

987x9+5=8888

9876x9+4=88888

98765x9+3=888888

987654x9+2=8888888

9876543x9+1=88888888

98765432x9+0=888888888

Guessing The Number (Just Playing Around)

noreply@blogger.com (Andri) — Sun, 07 Oct 2007 17:07:00 +0000

Here’s a trick that will make your friends think you can guess any number they think of.

-Choose a number between 0 and 50 and write it down on a piece of paper. Fold the paper and give it to a friend who mustn’t look at it.

-Ask your friend to choose a number between 50 and 100. He mustn’t let you know what it is.

-Subtract the number you had chosen (and written on the piece of paper) from 99.

-Ask your friend to add the result you get to the number he chose.

-He must then take off the first digit on the left and add it to the number.

-Then, ask him to subtract this number from the one he had originally chosen.

The resulting number will be the one you had written on the paper at the very beginning!

Small Village (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Sun, 07 Oct 2007 17:07:00 +0000

I live in a very small village where many people are related to each other. For example Tom, Dick and Harry are garage owner, vicar and solicitor but not in that order. Tom is the vicar’s father-in-law and Dick is the solicitor’s son-in-law. Everyone was at the church last Saturday when Harry married the garage owner’s daughter. Who does which job? (By the way, the people are very moral in our village, so none of the three has been married more than once.)

Again, in order to make it more interesting, I am not giving the answer or the clue straight, and this one is pretty tough. Please try to give your answer in the comment box at my blog or by email, I’ll check it out as soon as possible, and I’ll give the clue and the answer eventually. Thx guys!!

The Pawnbroker (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Sun, 07 Oct 2007 17:06:00 +0000

As I reached the ticket office I realized I had no cash, only a $10 postal order. The fare to Cambridge was $7 and the booking clerk would not accept my postal order. Luckily there was a pawnbroker nearby, so I went in and pawned my postal order for $7. On my way back into the station, I met Patrick, a friend of mine, who offered to buy the pawn ticket from me for $7, to save me the trouble of coming back to London. Naturally I agreed, then rushed in and bought my ticket. When I got to Cambridge I still had $7 of course.

So who lost?

Clue: If the man who travelled to Cambridge had been able to use his $10, he would have had $3 left after deducting the fare. Instead he has $7. So $4 has come from somewhere. In order to redeem the postal order, someone will have to pay the pawnbroker back his $7..

Answer: Patrick is the loser.

The Wrong Finger (Just Playing Around)

noreply@blogger.com (Andri) — Sun, 07 Oct 2007 17:05:00 +0000

Give a friend the following instructions:

-hold your arms in front of you

-cross them

-turn them so that your palms face each other

-clasp your hands tightly

-bend your elbows outwards

-bring your hands under your chin

Then point to one of his fingers (don’t touch it!) and ask him to move it. You will probably find that he will move the wrong finger. Ha-ha. Give it a try..

The Records (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Fri, 05 Oct 2007 08:04:00 +0000

Jack said, ‘if I had one of your records, I’d have as many you.’ Bob said, ‘If I had one of yours, I’d have twice as many as you!’ How many records had each?

Clue for the Puzzle: Try out one or two possible answers. For example, suppose Jack had three records, and Bob five. Then if Bob gives him one, each will have four. But if Jack gives one to Bob, he has six and Jack has only two. So that will not work. Try another pair of numbers in the same way.

Answer for the Puzzle: Jack has five records and Bob has seven.

The Prescription (logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Fri, 05 Oct 2007 08:03:00 +0000

Yesterday my doctor prescribed some tablets. There were five in the box. He told me to take one every half hour. How long did they last me?

Clue for the answer: What did I do as soon I get home?

Answer for the Puzzle: They lasted 2 hours.

The Bus and The Cyclist (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Fri, 05 Oct 2007 08:03:00 +0000

The bus from Edinburgh to London left at 8 a.m. An hour later a cyclist started out from London for Edinburgh. When the bus and the cyclist meet, which of the two will be further from Edinburgh?

Clue for the Puzzle: You don’t need math to solve this!!

Answer for the Puzzle: They are exactly the same distance from Edinburgh of course. Ha-ha..

Nine (Math Brainteaser Puzzle)

noreply@blogger.com (Andri) — Fri, 05 Oct 2007 08:02:00 +0000

How many times does the digit 9 appear between 1 and 100? Give the answer in 10 seconds!!

Answer for the Puzzle: 20 times

Fish Fingers (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Fri, 05 Oct 2007 08:01:00 +0000

I wanted to fry some fish fingers for myself and my two guests. I had three fish fingers but the frying pan only holds two at a time. it takes 30 seconds to fry one side of a fish finger. So how did I manage to fry both side of all three fish fingers in one and half minutes?

Clue for the Puzzle: Obviously I could not do it by frying two on one side and then on the other. Suppose I had fried two on one side and then taken out and replaced it with the third?

Answer for the Puzzle: I put in two and fried them on one side (30 seconds). I tool one out, turned one over and put the third in (30 seconds). Now I had one cooked on both sides and two cooked on one side. So I turned over the one in the pan and put back the one I had taken out earlier (30 seconds) and all three were cooked.

The Cheating Runners (logic Brainteaser Puzzles)

noreply@blogger.com (Andri) — Fri, 28 Sep 2007 07:56:00 +0000

When Alex, Brian and Chris finished their race they were feeling very tired. It had been raining very heavily, so heavily in fact that the judges were unable to see who came in first, who second and who third. When he asked the three men, they each made two statements. One man lied in both his statements. The other two told the truth. This is what they said:

Alex said, ‘I came in first, Chris was last.’

Brian said, ’Alex wasn’t first. Chris came in second.’

Chris said, ‘I was before Alex. Brian wasn’t second.’

So what was the order in which they crossed the finishing line?

Clue for the Puzzle: What Alex and Brian say about Chris disagrees. Therefore one of them must be lying.

Answer for the Puzzle: Alex and Brian say different things about Chris. Therefore one of them is lying and Chris must be telling the truth. Since Chris says he was before Alex, it is obvious that Alex is lying about coming first. Therefore the real order must have been Brian (who wasn’t second, according to Chris who told the truth), then Chris (Because Brian said so, and he also was telling the truth)-finally Alex.

The Local Bus (Math Brainteaser puzzles)

noreply@blogger.com (Andri) — Fri, 28 Sep 2007 07:52:00 +0000

The local minibus that runs from our village to the nearest town has the following seating regulations:

Maximum Capacity:

Sitting: 8 adults or 12 children

Standing: 2 adults or 4 children

As the last bus drew up at one of the stops on Saturday evening there were six adults who wanted to get on. But there were already seven children in the bus. How many of the adults would be able to get on the bus if the regulations were observed?

Clue for the Puzzle: If 12 children can sit in the same space as eight adults, how much room would three children take up?

Answer for the Puzzle: No problem! If 12 children can sit in the same space as eight adults then three children could sit in the same space for two adults. This meant that if four children stood up and three remained seated, there would still be room for the six adults to sit down. So everyone was able to get on.

Predicting the Color (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Wed, 26 Sep 2007 03:59:00 +0000

There are three boxes labeled ‘red balls’, ‘White balls’ and ‘red and white balls’. Each of the labels is incorrect. You are allowed to take one ball only from each box. How can you label each box correctly?

(Of course, you are not allowed to look inside!)

Clue for the Puzzle:

It will be sufficient to correctly identify one box. We know that all the boxes are incorrectly labeled. Once one box has been correctly identified, all we need to do is to switch the labels on the other two boxes.

Answer for the Puzzle:

The first thing to do is to take a ball from the box incorrectly labeled ‘red and white balls’. If it is red, then clearly this is the box containing red balls. If white, then white. Since we know that the boxes are all incorrectly labeled it is now sufficient to switch the two remaining labels.

Job Interview (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Wed, 26 Sep 2007 03:55:00 +0000

An employer was very anxious to find the most intelligent of the three men who had applied for a job. So he told them: ‘here are five conical hats. Three are white and two are black. I shall place a hat on each of your heads. When you turn around, you will be able to see the others’ hats but not your own. The first one to tell me the color of his own hat will get the job.’ He then placed a white hat on each man’s head. When the three men turned to face each other there was a long silence. Then, suddenly, one of the candidates said, ‘Mine is white.’

How did he know?

Clue for the Puzzle:

There are three possible combinations: two men had black hats and one a white one (this must be excluded because if one man had seen two black hats, he would immediately have known his was white); two had white hats and one had a black one; all three had white hats.

The secret is to work out the color of one’s own hat from what the other people must able to see.

Answer for the Puzzle:

He could see two white hats. Therefore he might have had on either a white or a black hat. He then reasoned like this: Suppose my hat is black. If it is, my two rivals A and B can each see a black hat and a white hat. One of them (A) might then work out that his own hat could not be black because, if it were, B would see two black hats and would know that his own hat must therefore be white. B says nothing however. A might therefore conclude, if my hat is black, then his own hat must be white. But since he does not come to this conclusion, then my assumption that my hat is black must be false. Therefore my hat must be white.

Ali the Thief (Survival Brainteaser Puzzle)

noreply@blogger.com (Andri) — Wed, 19 Sep 2007 04:02:00 +0000

Ali the thief had managed to break into the Sultan’s treasure room. He was looking for a bag containing 1250 diamonds, each weighing 0.8 grams. Unfortunately, the Sultan had filled nine other bags with imitation diamonds. There were 1000 in each bag, each one weighing 1 gram. So all 10 bags weighed exactly 1000 grams and all the bags looked exactly alike. Just as Ali was scratching his head, the Sultan burst in with his guards. As he was a merciful Sultan, he gave Ali a chance to save his life. Here is what he said; “If you can find the bag which contains the real diamonds by using these scales just once, you may keep the diamonds. If not, you will be beheaded. You can take stones from any of the bags and put them in other bags if you wish but you can only weigh once!”

How did Ali save his neck?

Clue for the Puzzle:

Suppose there were only three bags. If Ali took one stone from bag no. 1, two from bag no. 2, and three from bag no. 3 and weighed them together, would he be able to tell which the bag of diamonds was?

Answer for the Puzzle:

Ali put the bags in a row and removed one stone from the first bag, two from the second, three from the third, etc. He therefore had 55 stones. If all the stones weighed 1 gram, the total weight would be 55 grams. But Ali knew that some were 0.2 grams lighter. So supposing the total weight had been 54.6 grams, he would have known that it was bag no.2 which contained the diamonds (53 stones at 1 gram and two stones at 0.8 gram each = 1.6 grams). If the total had weighed 54.2 grams, he would have known it was the fourth bag he was looking for (51 stones at 1 gram and 4 stones at 0.8 gram each = 3.2 grams). In this way he could locate the bag with the real diamonds with no trouble at all.

No place like Vegas (Gambling Brainteaser Puzzle)

noreply@blogger.com (Andri) — Wed, 19 Sep 2007 04:01:00 +0000

Las Vegas is the place for gambling in America. I was just coming out of a Casino when a man came up to me and said “I’ll bet you $5 that if you give me $10, I’ll give you $15.” What do you think I did?

Clue for the Puzzle:

What would be the result if he lost the bet?

Answer for the Puzzle:

I told him to go and look for another fool to try it on! If I had accepted his bet and given him the $10, he would simply have said “I lose the bet.” He would then have given me the $5 he had bet me. But I would have lost the other $5 through my stupidity.

Two men (Tricky Brainteaser Puzzle)

noreply@blogger.com (Andri) — Wed, 19 Sep 2007 03:59:00 +0000

Two men were standing facing in opposite directions. Yet each one could see the other without turning around. How was that possible?

Clue for the Puzzle:

Which way were they looking if they could see each other?

Answer for the Puzzle:

They were facing each other.

Indians Family (Logic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Wed, 19 Sep 2007 03:58:00 +0000

Two Indians were talking to each other about their family relationships. The fat one said to the thin one, “Your father is my father’s son.” “That’s right.” replied the thin one, “and you yourself have neither sons nor brothers.” How were the two Indians related?

Answer for the Puzzle:

The thin one was the daughter of the fat father.

Dividing Cows (Math Brainteaser Puzzle)

noreply@blogger.com (Andri) — Wed, 19 Sep 2007 03:58:00 +0000

When farmer Jones died he left a herd of 17 cows. In his will he gave instructions that the cows were to be divided as follows: ½ to his eldest son, Sam, 1/3 to his second son, Michael, and 1/9 to his youngest son, Benjamin. The three brothers could not see how this was possible. Luckily for them, a passing professor of mathematics heard of this problem and solved it for them. How?

Clue for the Puzzle:

Suppose there had been 18 cows, how many each would the sons have got?

Answer for the Puzzle:

The professor of mathematics suggested they add one imaginary cow before doing their division:

½ of 18 = 9

1/3 of 18 = 6

1/9 of 18 = 2

Total = 9+6+2 = 17

Curiously enough, as you can see, this adds up to 17!

Jealous Men (Classic Brainteaser Puzzle)

noreply@blogger.com (Andri) — Wed, 19 Sep 2007 03:57:00 +0000

Three men with their wives come to a river. The boat they find can only take 2 people at a time. Because the men are all extremely jealous, no woman can be left with another man unless her own husband is also present. So how do they manage to cross the river?

Clue for the Puzzle:

Start off by A taking his wife across and coming back alone.

Answer for the Puzzle:

A takes his wife across and return alone. Then B’s and C’s wife cross together. A’s wife comes back. B and C then cross over and B comes back with his wife, leaving C and his wife on the far side. A and B then cross and C’s wife returns. A’s and B’s wives now cross. C rows back and fetches his wife.

Amoebas (Math Brainteaser Puzzle)

noreply@blogger.com (Andri) — Wed, 19 Sep 2007 03:55:00 +0000

Amoebas are a very simple form of life and are able to reproduce very quickly. It only takes three minutes for an amoeba to reproduce itself. In the laboratory there were two jars of equal size. In one of them there were two amoebas. It took them 3 hours to fill the jar. As an experiment, I placed one amoeba in the second jar. How long did it take to fill the jar?

Clue for the Puzzle:

After 3 minutes, there are two amoebas in the second jar too.

Answer for the Puzzle:

It takes 3 hours and 3 minutes for the second jar to be filled.