Question

В туристической группе 30 человек, 20 из них знают английский, 15 - французский. Сколько человек знают оба языка? Почему ответ 5 - неверный? Задача из ГИА

Answer 1

МАКСИМАЛЬНЫЙ ОТВЕТ ПОЛУЧАЕТСЯ:ОТ 5,ДО 15 ЧЕЛОВЕК

Answer 2

Calculating the Number of People Who Know Both Languages

To calculate the number of people who know both English and French, we can use the principle of inclusion-exclusion. We start by adding the number of people who know English and the number of people who know French and then subtract the total number of people in the group.

Step 1: Calculate the total number of people who know at least one language.

- Number of people who know English: 20 - Number of people who know French: 15 - Total number of people in the group: 30

Step 2: Apply the principle of inclusion-exclusion.

- Number of people who know at least one language = Number who know English + Number who know French - Number who know both languages - Number who know both languages = Number who know English + Number who know French - Total number of people

Let's calculate the number of people who know both languages using this formula.

Calculation: Number who know both languages = 20 + 15 - 30 Number who know both languages = 5

Why the Answer "5" is Incorrect

The answer "5" is incorrect because it represents the number of people who know both languages, not the number who know at least one language. The correct interpretation of the question should yield the number of people who know at least one language, which can be calculated using the principle of inclusion-exclusion as demonstrated above.

Therefore, the correct answer for the number of people who know both English and French is 5.