Question

Девочка стоит на первом этаже 14-этажного дома, на двенадцатом и на четырнадцатом этажах которого живут её подружки. Лестницы в доме нет, но есть лифт, который умеет перемещаться только на 3 или на 7 этажей вверх или вниз. Может ли девочка посетить всех подружек, совершив не более 6 переездов на лифте?

Answer 1

Вверх - 1+7=8+3=11+3=14 - 3 переездавниз - 14-3=11-3=8-3=5 - 3 переездавверх - 5+7=12 - 1 переезд3+3+1=7 переездовОтвет: за 6 переездов не может. И всё задача решенна

Answer 2

Problem Analysis

The problem states that a girl is standing on the first floor of a 14-story building, and her friends live on the twelfth and fourteenth floors. The building does not have stairs, but it does have a lift that can only move in increments of 3 or 7 floors up or down. The question is whether the girl can visit all her friends with no more than 6 elevator rides.

Solution

To solve this problem, we need to determine if it is possible for the girl to reach both the twelfth and fourteenth floors within 6 elevator rides. Let's analyze the possible scenarios.

Scenario 1: Reaching the Twelfth Floor First

If the girl reaches the twelfth floor first, she can then take the elevator to the fourteenth floor and return to the first floor. This scenario requires a total of 4 elevator rides: 1 to the twelfth floor, 1 to the fourteenth floor, 1 back to the first floor, and 1 more to reach the twelfth floor again. Therefore, this scenario is possible within the given constraints.

Scenario 2: Reaching the Fourteenth Floor First

If the girl reaches the fourteenth floor first, she can then take the elevator to the twelfth floor and return to the first floor. This scenario also requires a total of 4 elevator rides: 1 to the fourteenth floor, 1 to the twelfth floor, 1 back to the first floor, and 1 more to reach the fourteenth floor again. Therefore, this scenario is also possible within the given constraints.

Conclusion

Based on the analysis of the two scenarios, it is possible for the girl to visit all her friends, reaching both the twelfth and fourteenth floors, with no more than 6 elevator rides.