Question

В школе 2/5 всех мальчиков и 5/7 всех девочек ходят в кружок по программированию, причём известно, что количество мальчиков и девочек в нём одинаково. Какая доля всех школьников посещать кружок?

Answer 1

Ответ:

20/39

Объяснение:

2/5 всех мальчиков и 5/7 всех девочек ходят в кружок.

Количество мальчиков и девочек в кружке одинаково.

Найти долю всех школьников, которые ходят в этот кружок.

Решение:

Пусть мальчиков в школе x, а девочек y. Тогда:

2x/5 = 5y/7

14x = 25y

Пусть в школе x = 250 мальчиков и y = 140 девочек.

Тогда в кружке 2*250/5 = 100 мальчиков и 5*140/7 = 100 девочек.

Всего в кружке 100 + 100 = 200 из 250 + 140 = 390 школьников.

Доля школьников в кружке составляет:

200/390 = 20/39

Answer 2

Problem Analysis

We are given that 2/5 of all boys and 5/7 of all girls in a school attend a programming club. It is also mentioned that the number of boys and girls in the club is the same. We need to find the fraction of all students in the school who attend the club.

Solution

To find the fraction of all students in the school who attend the programming club, we need to calculate the fraction of boys and girls attending the club separately and then add them together.

Let's assume that there are b boys and g girls in the school. Since the number of boys and girls in the club is the same, we can say that 2/5 of b boys and 5/7 of g girls attend the club.

The fraction of boys attending the club is 2/5 of b, which can be written as (2/5) * b.

The fraction of girls attending the club is 5/7 of g, which can be written as (5/7) * g.

To find the total fraction of students attending the club, we need to add the fractions of boys and girls attending the club and divide it by the total number of students in the school.

The total number of students in the school is b + g.

Therefore, the fraction of all students attending the club is:

((2/5) * b + (5/7) * g) / (b + g)

Let's calculate this fraction.

Calculation

From the given information, we know that 2/5 of all boys and 5/7 of all girls attend the programming club. We also know that the number of boys and girls in the club is the same.

Let's assume there are b boys and g girls in the school.

The fraction of boys attending the club is 2/5 of b, which can be written as (2/5) * b.

The fraction of girls attending the club is 5/7 of g, which can be written as (5/7) * g.

The total number of students in the school is b + g.

Therefore, the fraction of all students attending the club is:

((2/5) * b + (5/7) * g) / (b + g)

To find the fraction of all students attending the club, we need to know the values of b and g. Unfortunately, the values of b and g are not provided in the question. Without this information, we cannot calculate the exact fraction of all students attending the club.

If you have the values of b and g, please provide them so that we can calculate the fraction for you.