Question

В классе мальчиков в два раза больше,чем девочек.Если из этого класса уйдут 4 мальчика,то мальчиков будет на 4 больше чем девочек.Сколько учеников в данном классе ?

Answer 1

х (уч.)  -  девочек

2х (уч.)  -  мальчиков

1) 2х - 4 = х + 4

  2х - х = 4 + 4

  х = 8 (уч.) - девочек

2) 2 * 8 = 16 (уч.) - мальчиков

3) 8 + 16 = 24 (уч.) - всего в классе - ответ.

Answer 2

Problem Analysis

We are given that there are twice as many boys as girls in a class. If 4 boys leave the class, the number of boys will be 4 more than the number of girls. We need to determine the total number of students in the class.

Solution

Let's assume the number of girls in the class is G. According to the given information, the number of boys in the class is twice the number of girls, so the number of boys is 2G.

If 4 boys leave the class, the number of boys will be 2G - 4, and the number of girls will remain the same, G.

According to the problem, the number of boys will be 4 more than the number of girls after 4 boys leave the class. So we can set up the following equation:

2G - 4 = G + 4

Now we can solve this equation to find the value of G.

Calculation

Let's solve the equation:

2G - 4 = G + 4

Subtract G from both sides:

2G - G - 4 = 4

Simplify:

G - 4 = 4

Add 4 to both sides:

G = 8

So the number of girls in the class is 8. Since there are twice as many boys as girls, the number of boys is:

2G = 2 * 8 = 16

Therefore, the total number of students in the class is:

G + 2G = 8 + 16 = 24

So there are 24 students in the class.

Answer

There are 24 students in the class.