Question

Над 30 парковочными местами горят лампочки ; зеленая над свободным местом и красная над тем ,где занято.На пустую парковку начали заезжать машины.Сперва красный загорелся над каждым 2-м по счету местом.Затем свет поменялся над каждым 3-м,а потом над каждым 5-м местом.Сколько осталосьпустых парковочных мест?

Answer 1

Сначала остались нечетные места.
Потом остались нечетные, которые не делятся на 3: 
1, 5, 7, 11, 13, 17, 19, 23, 25, 29.
И наконец, остались места, которые не делятся ни на 3, ни на 5.
1, 7, 11, 13, 17, 19, 23, 29.
Пустых мест осталось 8.

Answer 2

Problem Analysis

We are given a scenario where there are 30 parking spaces with light bulbs above them. A green light indicates that the parking space is available, while a red light indicates that the parking space is occupied. Cars start entering the empty parking spaces, and the lights change according to a specific pattern. We need to determine how many empty parking spaces are left.

Solution

To solve this problem, we need to analyze the pattern in which the lights change and calculate the number of empty parking spaces at the end.

Let's break down the given information step by step:

1. Initially, all 30 parking spaces are empty, so we have 30 green lights.

2. The red light above every 2nd parking space turns on. This means that the lights change from green to red for every 2nd parking space. After this step, we have 15 green lights and 15 red lights.

3. The lights above every 3rd parking space change. This means that the lights that were previously red will turn green, and the lights that were green will turn red. After this step, we have 10 green lights and 20 red lights.

4. Finally, the lights above every 5th parking space change. This means that the lights that were previously red will turn green, and the lights that were green will turn red. After this step, we have 6 green lights and 24 red lights.

Therefore, there are 6 empty parking spaces remaining.

Conclusion

After analyzing the given information, we determined that there are 6 empty parking spaces remaining.