Geekery

Riddles: Fuses and filling barrels

Posted on 25. Aug, 2009 by Jake.

Riddle – burning fuses

You have two slow-burning fuses, each of which will burn up in exactly one hour. They are not necessarily of the same length and width as each other, nor even necessarily of uniform width, so you can’t measure a half hour by noting when one fuse is half burned. Using these two fuses, how can you measure 45 minutes?

Answer: Two half-full barrels are dumped into one of the empty barrels. Two more half-full barrels are dumped into another one of the empty barrels. This results in nine full barrels, three half-full barrels, and nine empty barrels. Each son gets three full barrels, one half-full barrel, and three empty barrels.
You have two slow-burning fuses, each of which will burn up in exactly one hour. They are not necessarily of the same length and width as each other, nor even necessarily of uniform width, so you can’t measure a half hour by noting when one fuse is half burned. Using these two fuses, how can you measure 45 minutes?

Riddle – wine in barrels

A man is the owner of a winery who recently passed away. In his will, he left 21 barrels (seven of which are filled with wine, seven of which are half full, and seven of which are empty) to his three sons. However, the wine and barrels must be split so that each son has the same number of full barrels, the same number of half-full barrels, and the same number of empty barrels. Note that there are no measuring devices handy. How can the barrels and wine be evenly divided?

Answer:

Light one fuse at both ends and, at the same time, light the second fuse at one end. When the first fuse has completely burned, you know that a half hour has elapsed, and, more relevantly, that the second fuse has a half hour left to go. At this time, light the second fuse from the other end. This will cause it to burn out in 15 more minutes. At that point, exactly 45 minutes will have elapsed.

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Oldest Piano Player on a Railroad Bridge Riddle

Posted on 21. Aug, 2009 by Jake.

Think you’re fast? Time yourself solving these riddles, submit your time in the comments section (…those who tell the truth get a noddy badge!)

The Oldest Plays the Piano

Two MIT math grads bump into each other while shopping at Fry’s. They haven’t seen each other in over 20 years.

First grad to the second: “How have you been?”
Second: “Great! I got married and I have three daughters now.”
First: “Really? How old are they?”
Second: “Well, the product of their ages is 72, and the sum of their ages is the same as the number on that building over there…”
First: “Right, ok… Oh wait… Hmm, I still don’t know.”
Second: “Oh sorry, the oldest one just started to play the piano.”
First: “Wonderful! My oldest is the same age!”

How old was the first grad’s daughter?

Answer:

The possible ages ( factors of 72 ) and their sums are shown below:
Ages:            Sum of ages:
1 1 72            74
1 2 36            39
1 3 24            28
1 4 18            23
1 6 12            19
1 8 9             18
2 2 18            22
2 3 12            17
2 4 9             15
2 6 6             14
3 3 8             14
3 4 6             13

We can deduce from the man’s confusion over the building number that this wasn’t enough information to solve the problem. The chart shows the sum 14 twice for two different age possibilities, which would explain how knowing the building number alone would not have given him the answer. The clue that the “oldest one” started to play the piano rules out “2 6 6” as an answer, because there is no “oldest”. Since the first grad was certain with the piano clue, the first grad’s oldest daughter is 8. I’ll leave it up to the reader to figure out why this doesn’t necessarily mean the second grad’s oldest daughter was also 8.

Railroad Bridge

A man needs to go through a train tunnel.  he starts through the tunnel and when he gets 1/4 the way through the tunnel, he hears the train whistle behind him.  You don’t know how far away the train is, or how fast it is going, (or how fast he is going).  All you know is that:

1. if the man turns around and runs back the way he came, he will just barely make it out of the tunnel alive before the train hits him,
2. if the man keeps running through the tunnel, he will also just barely make it out of the tunnel alive before the train hits him.

Assume the man runs the same speed whether he goes back to the start or continues on through the tunnel.  Also assume that he accelerates to his top speed instantaneously.  assume the train misses him by an infintisimal amount and all those other reasonable assumptions that go along with puzzles like this so that some wanker doesn’t say the problem isn’t well defined.

How fast is the train going compared to the man?

Answer:

We know that the train and man will reach the start of the tunnel at the same time if the man turns around, in that time the man travels 1/4th the length of the tunnel. 

If the man travels on towards the end of the tunnel he will be able to travel an additional 1/4th of the length of the tunnel before the train reaches the start of the tunnel, putting the man at the half way point.

For both the man and the train to reach the end of the tunnel at the same time, the man has to travel 1/2 the length of the tunnel while the train has to travel the full length of the tunnel.

Therefore the train must be travelling twice as fast as the man (and as an aside must have been half the length of the tunnel away from the start of the tunnel when it blew its whistle).

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Riddles: Prom night & unscramble the word

Posted on 14. Aug, 2009 by Jake.

Riddle: What’s the word?

What does this say???

Leheve

Answer:

Heavenly   [hev in lee]

Riddle: Who’s dating who on prom night?

Next Saturday is Senior Prom Night for the Millersville High School. This always-anticipated event has had the student gossip buzzing all week. While many of the couples going were no surprise, as they’d been dating awhile, some couples would make the Senior Prom their first date. Determine the full name of each couple, and whether the Senior Prom is each couple’s first date or if they’d been dating previously.

1. Dave Larsen didn’t ask Ms. Green to the prom. Mr. Finch went to the prom with Ms. Jenson.

2. Thomas and the girl he asked to the prom had been dating previously.

3. The three couples who had not been dating previously were Mr. Barr and Susan, Joe and Maryann, and Ms. Swift and Edward.

4. Cindy Parker didn’t go to the prom with Thomas but she did go with a boy she had dated previously.

5. Collette, whose last name wasn’t Green, went to the prom with the boy whose last name was Mann.

6. Mr. Leach, whose first name wasn’t Joe, went to the prom with a girl he hadn’t dated before

Answer:

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Riddles: phone numbers and test yourself

Posted on 05. Aug, 2009 by Jake.

Riddle: phone numbers

There is a town in Texas where 5% of all the people living there have unlisted phone numbers. If you selected 100 names at random from the town’s phone directory, on average, how
many of these people would have unlisted phone numbers?

 Answer: None. You will not find unlisted phone numbers in a phone directory.

Riddle: mental test

It doesn’t hurt to take a hard look at yourself from time to time. This little test should help you get started.

During a visit to a mental asylum, a visitor asked the Director what the criteria is that defines if a patient should be institutionalized.

“Well,” said the Director, “we fill up a bathtub. Then we offer a teaspoon, a teacup, and a bucket to the patient and ask the patient to empty the bathtub.”

Okay, here’s your test:
1. Would you use the spoon?
2. Would you use the teacup?
3. Would you use the bucket?

“Oh, I understand,” said the visitor. “A normal person would choose the bucket, as it is larger than the spoon.”
What was the director’s response?

Answer: ”No,” answered the Director. “A normal person would pull the plug.”

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Riddles:Horses and Guesses

Posted on 24. Jul, 2009 by Jake.

Riddle: Travelling horse

A horse travels a certain distance each day. Strangely enough, two of its legs travel 30
miles each day and the other two legs travel nearly 31 miles. It would seem that two of the horse’s legs must be one mile ahead of the other two legs, but of course this can’t be true. Since the horse is normal, how is this situation possible?

Answer:

The horse operates a mill and travels in a circular clockwise direction. The two outside legs will travel a greater distance than the two inside legs.

Riddle: What am I?

My first is in blue, but not in glue,
My second in old, but not in new.
My third in look, but not in see,
My last in ask, but not in plea.
My whole has leaves but not a flower,
I’ll help you pass an idle hour.
What am I?

Answer:   A Book

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