- Sister “A” was born two years after the birth of her older twin brother B. How come?
- One day “A” celebrated her birthday. Two days later her older twin brother, “B”, celebrated his birthday. How come?
- A asked B: “I say something. If it is truthful, will you give me your silver coin?”
“Yes,” replied B.
“And if it is a lie, do not give me your silver coin. Would you promise that?”
B agreed. Then A said such a sentence that after a little while of thinking B realized, that if he wanted to honor his promise, he wouldn’t have to give her a silver coin but a gold coin.
What would you say (if you were A) to get the gold coin?
[This puzzle was originally published in my book “Out of Box Computational Thinking Puzzles”. Find more interesting puzzles (including from that book) on this link. Also, don’t forget to check my puzzle books “Computational Puzzles To Flex Your Brain: 50 original puzzles to sharpen computing mind and mathematical skills” and “Brain Teasers with Coding For Data Scientist 2: 9 New Computational Puzzles” and “Puzzles with Coding: Puzzles for Everyone” at Amazon. For purchasing my books or related queries, feel free to contact me. Even in coding puzzle books, you will find interesting puzzles those are suitable for coders as well as non-coders. Coding solutions are also provided with Python code. So, grab a copy of those books and jump into the world of fascinating and exciting puzzles.]
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Solution:
1.) In widely used Julian calendar, we do not have a ‘year 0’. After 1 BC, the following year is 1 AD.
So, older brother B was born on the last day of year 1BC just before 12 PM while sister A was born on the first day of year 1AD just after 12 PM (next day). So A was born in 1BC, mathematically two years before sister B who was born in 1AD.
2.) Brother B was born on March 1 (in a non-leap year) on a plane flying eastwards over the Pacific. A few seconds later the plane crosses the International Date Line, and sister A was born. She was thus born on February 28, making her the ‘younger’ sister with a calendar birth date one day before her brother’s. On leap years, however, A will celebrate her birthday two calendar days before her older twin.
3.) Your statement should be – “You will give me neither a silver coin nor a gold coin.”
