The worlds first riddle!

Why should M be 1??

Why should M be 1??

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Money

9567
1085
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10652

what abou this one

ABCD
4
-------x
DBCA

find the numbers ABCD

I'm not sure if I understand it - does it mean: ABCD x 4 = DBCA?

yes it means ABCD*4=DBCA

I am at my office and so far I suppose A is surely 2, and D 3 or 8, but I'll have to continue thinking later

I didn't knew the answer either but I think that this doesn't have any solution


cause A=2
then D=8
then C=9

and after that you are stuck

I still haven't think about it, but D can be 3 also - I must admit that I also think that it's impossible, unless maybe some letters may be same number (like, both A and C are 2 for example) - but I haven't calculate too much, it's just obvius that A has to be 2 (because when multiplying with 4 every number bigger then 2.500 would give 5 digit number - and A can't be 1, because there is no number that gives 1 when multiplied with 4 - so A is 2, and that means that D has to be 3 or 8 - because those two numbers multiplied with 4 are only that give 2 - (1)2 and (3)2

do the 3 numbers be in the same order in serialnumber

example: if i choose 567
and that the serialnumber is 12345678????

and can the serialnumber contain the same number---->11111111????

but so far i've found this answer

1/2480

The question is basically about the chance of selecting three numbers out of a random selection of eight. This is an old problem and the answer given is based on 7-8-9.
Although, I do wonder if lower numbers would give a better chance. In 'real life' I am sure it would.
However the original question does state ", you may assume that an equal number of each combination is in circulation." I will post the full answer tomorrow.

If you will wait with your answer i can work it out :wink:

i still think that i don't understand the question completely,

if the three numbers i choose must be in the same order that i picked them, then you have 8!/5! ways of putting that order in 8 digit number.

if not there just 120 combinations of choosing randomly 3 numbers out of 10

As promised;( The fault is mine, the question could have been worded better.)

You pick three different numbers from 0 to 9. What is the probability that a dollar bill chosen at random will contain all 3 of your numbers in the serial number? Note: the serial number has 8 digits, you may assume that an equal number of each combination is in circulation.

Let's answer the question what is the probability that the bill does NOT contain all three numbers. Let's assume that our three chosen numbers are 7, 8, and 9.
The number of ways the serial number can contain none of the three numbers, or be composed of only digits 0 to 6 is 78.
The number of ways the serial number can contain at least one 7 but no 8 or 9 is 88-78. We must subtract 78 because there are that many numbers that contain only the digits 0 to 6 but no 7. Likewise the number of ways to add at least one 8 or one 9 is also 88-78. So the number of ways the serial numbers will contain just one digit out of {7,8,9} is 3*(88-78).
Now let's consider the number of ways the serial number can have at least one 7 and 8 but no 9. The number of all combinations leaving out the 9 is 98. However, some of those have no 7 or 8 digits. The number of combinations with 7 but no 8 is 88-78. This is also the number of combinations with 8 but no 7. We must also subtract the number of combinations with only 0-6, which is 78. So the number of combinations with at least one 7 and one 8, but no 9, is 98-2*(88-78)-78. Multiply this by three for the number of ways the serial number can omit the 7 and 8 but leave the other two chosen numbers. So the probability the serial number will have 2 out of our 3 numbers is 3*(98-2*(88-78)-78).
So the probability that the serial number will not contain all three chosen numbers is:
(78 + 3*(88-78) + 3*(98-2*(88-78)-78)))/108 =
(3*98-3*88+78)/108 = 0.84573316.
To get the probability will contain all three chosen numbers just subtract the number above from one, or 1 - (3*98-3*88+78)/108 = 0.15426684.


In response to requests as to what I found the hardest riddles. I give you a laugh by posting my failures. Some look very easy now, but not back then. Can you do better than I did?

Forty men found themselves in a desperate situation, and all but two of them decided that they should kill themselves. Unable to dissuade the group, the two men who refused to give up pretended to go along with the group's plan. They even suggested a way in which death can take place in an orderly manner.

Here is their idea: all forty men should sit in a circle, and, starting with someone who wanted to go first, every third person in the circle would follow; the counting would go around till the last man, who would commit suicide. The two men thought that if they placed themselves at certain points in the circle, all others in the group would have died before them. For their scheme to work, where in the circle should they sit



Tom went to a party one night. The next day he was asked if he met a lot people at the gathering. "Figure it out for yourself," Tom said. "Of the girls I spoke to, all but two were blondes, all but two were brunettes, and all but two were redheads." How many girls did he talk to

To be continued…

Tom talked to three girls.

i do not agree with you

Quote, "Tom talked to three girls."

Quote, "I do not agree with you." You would not be the first, or the last. Please feel free to correct any mistakes.

Page 18 Baseball Team.

Solution

Harry is the pitcher, Allen the catcher, Paul the first baseman, Jerry the second baseman, Andy the third baseman, Ed the shortstop, Sam the left fielder, Mike the right fielder, and Bill the center fielder.

This one I thought I answered.
A wealthy wise old woman feared that her daughter was lazy and as a result rather stupid. When the old woman died, her will stipulated that her assets were to be liquidated and a check was to be written for the full amount. The check was to be placed in one of three envelopes. The other two envelopes would contain a blank piece of paper. If the daughter could determine from the writing on the envelope which envelope contained the check, she would inherit her mother's fortune. Otherwise, the fortune would go to the old woman's favourite charity for animals. The daughter was not allowed to touch the envelopes. Her decision had to be made based on the writing on the envelopes. The daughter was told that only one envelope had a true statement and that the other two statements were false.

The envelopes had the following writing:

1. This envelope does not have the check
2. This envelope has the check
3. The second envelope does not have the check

Which envelope should the daughter pick?

If envelope 2 is true then envelope 1 must also be true. So 2 = f.
If 2 = f then 3 must be true so 1 = f.
Therefore the money is in envelope 1.

In other words;
The daughter should pick envelope 1. Unfortunately, she picked envelope 3. Statements 1 and 2 were false, and the only true statement was statement 3.
If the check was in envelope 1, that would make statement 1 false, statement 2 false and statement 3 is the only true statement

Somewhere in the pile;
Five former classmates sat together at a round table at their ten-year college reunion. Each woman had an entrée and a dessert and in front of her was a flower in a vase. Erin and Ms. Gaynes ordered seafood fettuccini. Michelle and Miss. Browne had salmon. One woman had halibut. Erin and Mrs. Daniels had chocolate mousse. Melissa and Ms. Smythe ordered a sundae. Miss. Browne had a bread pudding. Michelle and Mrs. Andrews each had a rose.
Sandy and Miss. Browne each had a carnation. Only one woman had an orchid. No two women sitting next to each other had the same entrée, dessert or flower. What did Lila eat?


'WTF'

Sandy Smythe, halibut, Sundae, carnation.
Erin Andrews, Fettucini, mousse, rose.
Lila Browne, salmon, bread pudding, carnation.
Melissa Gaynes, fettucini, sundae, orchid.
Michelle Daniels, Salmon, mousse, rose.


Another riddle I did not get anywhere near to the answer.

It is said that at a great temple in South Asia, there is this sacred Tower, a device with which priests there mark the time remaining till the end of the whole world. The tower consists of 3 diamond needles standing upright, around one of which 64 golden plates with holes in the centre have been placed, one atop another. The disks in the stack are placed according to their sizes, with the biggest at the bottom, and the smallest topmost. Day and night priests at the temple transfer the golden plates thus stacked to the other two needles, always observing the rule that no larger plate shall be placed on a smaller plate. It is believed that when all of the 64 plates have been transferred onto another needle, in its original arrangement, namely the biggest at the bottom and the smallest topmost, the world comes to its end. Suppose the priests can move one plate a second, how long will it be before they reach the fatal moment