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There are people and strange monkeys on this island, and you can not
tell who is who (Edit: until you understand what they said - see
below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.
Know who are they!
What was the situation?
Let's first have statements by 2 creatures -
A: B is a lying monkey. I am human.
B: A is telling the truth.
If we assume B is telling the truth then A is also telling the truth. But A in statement says B is lying which contradicts our assumption.
Hence, B must be lying. If B is lying then statement of B suggest that A is also must be lying. That mean 'B is lying monkey' part of statement made by A is too lie. Since we have deduced already B is lying, the lying statement of A suggests that B is not monkey. Hence B is the lying man!
Other lie spoken by A is that it is human. Hence A must be a lying monkey!
Today, John has to transfer 50 euro to the bank account of a Dutch
friend. He has written down the account number on a piece paper. But
since he had forgotten to take out the paper from his trousers when he
put them in the washing machine, one digit of the bank account number
became unreadable. The note says: 3170?4847.
The friend of John is
climbing the Mount Everest at the moment, so it is impossible for John
to call his friend. Suddenly he remembers that a for a valid Dutch bank
account number it holds that the first digit times 9 + the second digit
times 8 + the third digit times 7 + ...... + the ninth digit times 1
should be divisible by 11. John thinks for a moment and finds the
correct number.
What is it?
That it is !
What were the clues?
Let x be that missing digit. Then the bank account number looks like, 3170x4847.
Now 9 x First Digit + 8 x Second Digit + 7 x Third Digit.......must be divisible by 11.
That is 27 + 8 + 49 + 0 + 5x + 16 + 24 + 8 + 7 = 139 + 5x must be divisible by 11.
The only value of x as a digit the satisfies above is 3. With that, total sum 154 is divisible by 11.
Hence, the account number must be, 317034847.
