Question

В течении нескольких дней 1) дождь шелВ течении нескольких дней 1) дождь шел 7 раз либо утром либо вечером; 2) если дождь шел вечером, то утром было ясно; 3) если дождь шел вечером, то утром было ясно; 4) 6 раз утром было ясно; 5) 5 раз вечером было ясно. За какое наименьшее количество дней могли произойти все эти явления? А. за 7; Б. За 8; В. За 9; Г За 10. Помогите пожалуйста!

Answer 1

Ответ 9 дней так что ( в ) 

Answer 2

Problem Analysis

We are given the following information: 1. Rain fell for several days, either in the morning or in the evening. 2. If it rained in the evening, then it was clear in the morning. 3. If it rained in the evening, then it was clear in the morning. 4. It was clear in the morning 6 times. 5. It was clear in the evening 5 times.

We need to determine the minimum number of days in which all these events could have occurred.

Solution

Let's analyze the given information step by step:

1. Rain fell for several days, either in the morning or in the evening. 2. If it rained in the evening, then it was clear in the morning. 3. If it rained in the evening, then it was clear in the morning. 4. It was clear in the morning 6 times. 5. It was clear in the evening 5 times.

From statements 2 and 3, we can conclude that if it rained in the evening, it was clear in the morning. Therefore, the number of times it rained in the evening is equal to the number of times it was clear in the morning.

Let's consider the possibilities:

- If it rained in the evening 0 times, then it was clear in the morning 0 times. - If it rained in the evening 1 time, then it was clear in the morning 1 time. - If it rained in the evening 2 times, then it was clear in the morning 2 times. - If it rained in the evening 3 times, then it was clear in the morning 3 times. - If it rained in the evening 4 times, then it was clear in the morning 4 times. - If it rained in the evening 5 times, then it was clear in the morning 5 times. - If it rained in the evening 6 times, then it was clear in the morning 6 times. - If it rained in the evening 7 times, then it was clear in the morning 7 times.

From statement 4, we know that it was clear in the morning 6 times. Therefore, the maximum number of times it rained in the evening is 6.

From statement 5, we know that it was clear in the evening 5 times. Therefore, the maximum number of times it rained in the morning is 5.

To satisfy all the given conditions, we need to find the minimum number of days in which it rained in the evening 6 times and in the morning 5 times.

Therefore, the minimum number of days in which all these events could have occurred is 11.

Answer: В. За 9.