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The worlds first riddle!

 
 
thoh13
 
  1  
Reply Thu 3 Jan, 2008 02:33 am
epenthesis wrote:
I'd forgotten that the product of 6 on 5, 5 on 4, and 3 on 2, equals the sum of the products.


what does that mean? product of a on b?
0 Replies
 
Tryagain
 
  1  
Reply Thu 3 Jan, 2008 09:04 am
Going to church doesn't make a presidential candidate a Christian any more than standing in a garage makes me an automobile. So if you think things can't get any worse, it's probably only because you lack sufficient imagination.



Teh Meh:


7-11

$3.16 as one of the numbers! Cool Cool

Well done, that was the hardest part.

"21"

Half right! :wink:


TTH:

I got the other 3 to be $1.20, $1.25 & $1.50 Cool Cool Cool

"Can you explain the answer so I can understand it?"


Sure thing doll; there's only one possible solution, namely:

7.11 = 3.16 + 1.25 + 1.50 + 1.20 = 3.16 x 1.25 x 1.50 x 1.20


Proof :
If a, b, c, d are the prices of the items expressed in (whole) cents, what we are told is that a+b+c+d = 711 and abcd = 711000000 = 2^6 3^2 5^6 79.

So, one (and only one) of the amounts, say a, is a multiple of 79. This is, of course, less than 9 times 79 (which is 711), and may thus only be 1,2,3,4,5,6, or 8 times 79 (7 times 79 is ruled out, because it does not divide 711000000). These 7 possibilities translate into the following equations:

1. a=79, b+c+d=632, bcd=9000000
2. a=158, b+c+d=553, bcd=4500000
3. a=237, b+c+d=474, bcd=3000000
4. a=316, b+c+d=395, bcd=2250000
5. a=395, b+c+d=316, bcd=1800000
6. a=474, b+c+d=237, bcd=1500000
7. a=632, b+c+d=79, bcd=1125000

Now, the product of 3 positive numbers of given sum is greatest when they are all equal, which means that the product bcd cannot exceed (b+c+d)^3/27. This rules out the last three of the above 7 cases.


In the first three cases, on the other hand, the sum b+c+d isn't a multiple of 5, so at least one of b,c,d (say d) isn't either. Therefore, the product bc must be a multiple of the sixth power of 5. Since neither b nor c can be large enough to be a multiple of the fourth power [625 is clearly too big a share of 711, leaving only 7 cents for two items in the first case and nothing at all in the other two] we must conclude that both b and c are nonzrero multiples of 125. The number d would thus be obtained by subtracting from one of three possible sums (632, 553, 474) some multiple of 125 (necessarily: 250, 375 or [in the first two cases] 500). This gives only 8 possible values for d (382, 257, 132, 303, 178, 53, 224, 99). Each is unacceptable because it has a prime factor other than 2 or 3.

Therefore, only the fourth case is not ruled out, so that a=$3.16.
a=316, b+c+d=395, bcd=2250000.

Since the sum b+c+d is a multiple of 5, and at least one of the terms is a multiple of 5, either only one is, or all are. The former option is ruled out since this would imply for the single multiple of 5 to be a multiple of 5^6=15625, which would, by itself, be much larger than the entire sum of 395. So, b, c, and d are all multiples of 5, and we may let b=5b', c=5c', d=5d', where b'+c'+d'=79 and b'c'd'=18000.

Now, these three new variables may not be all divisible by 5 (otherwise their sum would be too). It's not possible either to have a single one of them divisible by 5, because it would then have to be a multiple of 5^3=125 and exceed the whole sum of 79.

Therefore, we must have a multiple of 25 (say b'=25b") and a multiple of 5 (say c'=5c"): 25b"+5c"+d'=79 and b"c"d'=144. It is then clear that b" can only be 1 or 2. If b" was 2, then we would have 5c"+d'=29 and c"d'=72, implying that c" is a solution of x(29-5x)=72 or 5x^2-29x+72=0. However, this quadratic equation does not have any real solutions, because its discriminant is negative. Therefore, b" is equal to 1 and b=5(25b")=125=$1.25.

The whole thing thus boils down to solving 5c"+d'=54 and c"d'=144, which means that c" is solution of x(54-5x)=144 or 5x^2-54x+144=0. Of the two solutions of this quadratic equation (x=6 and x=4.8), we may only keep the one which is an integer. Therefore c"=6, c'=30, c=150=$1.50.

Finally, d'=144/c=24 which means d=5d'=120=$1.20.

Therefore, the solution is unique (the order of the 4 items being irrelevant): $3.16, $1.25, $1.50, $1.20.



Slippy:

FLAGS
Permute me to suggest: P(7,2) = 7! / (7-2)!

ie. 7x6 Cool


"Permute" That is one heck of an expensive education you have there, I am pleased to see it is not going to waste. Very Happy


For those of us from the other side of the tracks; there are seven choices for the flag on top. There are six remaining choices for the flag below.

The Counting Principle says that the total number of ways is the number of choices for choice 1 times the number of choices for choice 2.

7 ways x 6 ways = 42 ways…Works every time!



A mother (please don't assume I am referring to Miss mi) and son have the same birthday; October 20. On that day the mother becomes 42 and her son becomes 11.

In what year will the mother be exactly twice as old as the son Question




29 = D in F in a L Y Question

32 = D F at which W F Question

40 = D and N of the G F Question
0 Replies
 
mismi
 
  1  
Reply Thu 3 Jan, 2008 09:08 am
29 = D in F in a L Y = 29 days in February in a Leap Year

32 = D F at which W F ? working on this one

40 = D and N of the G F = 40 days and nights of the Great Flood
0 Replies
 
mismi
 
  1  
Reply Thu 3 Jan, 2008 09:26 am
32 = D F at which W F = 32 degrees farenheit at which water freezes - yahoo!
0 Replies
 
mismi
 
  1  
Reply Thu 3 Jan, 2008 09:40 am
Have y'all seen this one before?



A man in a restaurant asked a waiter for a juice glass, a dinner plate, water, a match, and a lemon wedge. The man poured enough water onto the plate to cover it.
"If you can get the water on the plate into this glass without touching or moving this plate, I will give you $100," the man said. "You can use the match and lemon to do this."
A few minutes later, the waiter walked away with $100 in his pocket. How did the waiter get the water into the glass?
0 Replies
 
TTH
 
  1  
Reply Thu 3 Jan, 2008 10:09 am
I haven't seen that one mismi40. I don't know how it was done.
0 Replies
 
TTH
 
  1  
Reply Thu 3 Jan, 2008 10:14 am
epenthesis wrote:
TTH wrote:
TehMeh wrote:
I came up with 316 or $3.16 as one of the numbers!
Based on one of the numbers being $3.16, I got the other 3 to be $1.20, $1.25 & $1.50
That was just guessing at #'s. I don't know a formula for it and I have no idea how TehMeh came up with $3.16 to begin with Confused

Try, can you explain the answer so I can understand it?


Ooo go ogle googurl?

I'd forgotten that the product of 6 on 5, 5 on 4, and 3 on 2, equals the sum of the products.
How did you come up with 6/5, 5/4 & 3/2 for the answer to the problem? If I googled the problem, I am sure I could also find an explanation Exclamation
0 Replies
 
TTH
 
  1  
Reply Thu 3 Jan, 2008 11:15 am
I found the answer mismi40. I wouldn't have even guessed that answer Laughing
0 Replies
 
mismi
 
  1  
Reply Thu 3 Jan, 2008 11:53 am
Me either...amazing, can't wait to try it with the kids!
0 Replies
 
Tryagain
 
  1  
Reply Thu 3 Jan, 2008 01:27 pm
Miss mi:

29 = D in F in a L Y = 29 days in February in a Leap Year Cool

32 = D F at which W F = 32 degrees Fahrenheit at which water freezes Cool

40 = D and N of the G F = 40 days and nights of the Great Flood Cool

Congratulations you win today's star prize. Send me your personal, security and bank details together with a pinup picture to claim your second hand book token! Laughing

Restaurant riddle:

I have simply no idea Embarrassed ; but I know the answer to these:


What gets wetter and wetter the more it dries Question

Give me food, and I will live; give me water, and I will die. What am I Question

The man who invented it doesn't want it. The man who bought it doesn't need it. The man who needs it doesn't know it. What is it Question
0 Replies
 
markr
 
  1  
Reply Thu 3 Jan, 2008 02:22 pm
MISMI40'S WATER RIDDLE
[size=7]Place the lemon on the plate.
Light the match and place it in the lemon (the lemon is only used to hold the match).
Place the glass over the match/lemon (upside down).
Wait.
[/size]
0 Replies
 
mismi
 
  1  
Reply Thu 3 Jan, 2008 02:39 pm
amazing Mark - don't you think that will be fun to do with the kids? I wonder if it will really work?
0 Replies
 
Tryagain
 
  1  
Reply Thu 3 Jan, 2008 03:17 pm
Miss mi, I don't think that would be a good idea, kids don't burn so well…Stick to matches! Laughing
0 Replies
 
mismi
 
  1  
Reply Thu 3 Jan, 2008 04:08 pm
Oh my side...funny Razz
0 Replies
 
TTH
 
  1  
Reply Thu 3 Jan, 2008 05:35 pm
Tryagain wrote:
..... but I know the answer to these:

What gets wetter and wetter the more it dries Question

Give me food, and I will live; give me water, and I will die. What am I Question

The man who invented it doesn't want it. The man who bought it doesn't need it. The man who needs it doesn't know it. What is it Question
I also know the answer to those Laughing

Tryagain wrote:
Miss mi, I don't think that would be a good idea, kids don't burn so well…Stick to matches! Laughing
Now that is funny, good one Try Laughing Laughing
0 Replies
 
Tryagain
 
  1  
Reply Thu 3 Jan, 2008 05:53 pm
After the laughter…the tears: :wink:

A cable TV company has two channels of programming that it can offer (at negligible marginal cost) to a large pool of potential customers. Suppose the value (per unit time) of each channel to each potential customer is an independent random variable uniformly distributed on the interval (0,1) and that value is additive (so the value of both channels to the potential customer is the sum of the values of each individual channel). Assume a potential customer will buy when the (additional) value is greater than the (additional) price.

Suppose the company prices each channel independently. What should it charge for each channel (to maximize revenue) and what will its expected revenue be (per potential customer per unit time) Question



The product of three natural numbers is 24. How many different ways can this be done if the order of the 3 numbers does not matter Question
0 Replies
 
Tryagain
 
  1  
Reply Thu 3 Jan, 2008 05:55 pm
Hey! Three green words…I think I get ten bucks for that! Razz
0 Replies
 
mismi
 
  1  
Reply Thu 3 Jan, 2008 06:00 pm
I only see one...you have 1000 pages now...WOW! :wink:
0 Replies
 
TTH
 
  1  
Reply Thu 3 Jan, 2008 06:00 pm
Tryagain wrote:
Hey! Three green words…I think I get ten bucks for that! Razz
Confused I don't see 3 green words Confused
0 Replies
 
Tryagain
 
  1  
Reply Thu 3 Jan, 2008 06:09 pm
Cheapskates; they have taken them off…there goes my lunch tomorrow! Crying or Very sad

Better yet, the next post hits 10,000. Now that is really something! Razz
0 Replies
 
 

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