How long does it take a wife to drink a three-liter jar of juice alone? Bashny.Net

It is one thing in mathematics classes to puzzle over odd equations or similar examples, and quite another to solve fascinating problems that have at least some connection with real life. It is not surprising that even in adulthood, sometimes you want to take up the old and test your wit. So today's editorial office. "Site" offer logic. Can you decide?



Logic Problems with Answers

1. The first task should compute. However, only 35 digits were used to number all pages (from the first to the last). How many pages are there?
2. The second task is to determine the age of three men. We are talking about his grandfather, his son, and his grandson. At the same time, it is known that the grandfather and son together are 84 years old, and the grandfather and grandson are 64 years old. If you add up the age of the grandson and his father, you get 38 years.
   
   
   
   
3. Under the condition of the third task, the voracious husband drinks a 3-liter can of tomato juice in 14 minutes. He and his wife drink the same can in 10 minutes. How long does it take a wife to drink a 3-liter can of juice alone?
   
   
   
   

Answers to challenges

1. To find a solution, it is enough to include logic and note that only from the first to the ninth page we will use one digit for numbering, and then two. So 35-9 = 26 is the number of digits that we're going to spend on page 10. 26/2 = 13 pages where we need two digits to number. So, the number of all numbered pages 9 + 13 = 22. It's such a thin book.
   
   
   
   
2. Since the age of the grandfather + the age of the son = 84, and the age of the grandfather + the age of the grandson = 64, the son is older than the grandson by 84 - 64 = 20 years. Then the age of the grandson (38-20) / 2 = 9. And the age of the son is 9 + 20 = 29. Then the age of the grandfather is not so difficult to find: 84 - 29 = 55 years.
   
   
   
   
3. It's hard to imagine a husband and wife drinking whole. jar in 14 minutes, but we'll try. Since both together and alone they drink the same can of juice, the size of the container can not be taken into account. If both husband and wife drank at the same rate, they would drink a can of tomato juice in 14/2 = 7 minutes. If they drink a jar in 10 minutes, it means that the wife drinks slower than her husband. But how much? The husband drinks 10 / 14 volumes of juice in 10 minutes. So, the remaining 4 / 14 volumes in 10 minutes is drunk by the wife. From this it is easy to determine that it will take 14/4 * 10 minutes = 35 minutes of time if she drinks tomato juice with the usual appetite.
   
   
   
   
   
   

We hope that solution It was interesting and made me think. Write down how you found the answers. Who knows, maybe we made a mistake somewhere, and your solution will be the easiest or the most correct one.