Question

Девочки составляют 40% учеников класса. Отличники составляют 25% числа девочек , причем отличников на 20 меньше чем мальчиков.Найти количество учеников в классе.

Answer 1

1/7 * 3/5 = 3/35 всего класса - девочки-отличницы 
Количество девочек - число целое, значит, в класе 35 человек, из них 3 отличницы 

(в теории может быть 70 учеников, из них 6 отличниц; 105 учеников, из них 9 отличниц - но таких больших классов не формируют) 

21 - девочки (3 из них-отличницы) 
14 - мальчиков

Answer 2

пусть х - число всех учеников

0,4 х - число девочек

0,25*0,4х=0,1х - число отличников

(х-0,4х) - 0,1х =20

0,6х -0,1х=20

0,5х=20

х=40

Answer 3

Calculating the Number of Students in the Class

To find the number of students in the class, we can use the given information about the percentage of girls, the percentage of top students, and the difference in the number of top students between boys and girls.

Let's denote: - Total number of students in the class as T - Number of girls as G - Number of top students as O - Number of boys as B

We are given the following information: 1. Girls make up 40% of the class. 2. Top students make up 25% of the girls. 3. The number of top students among girls is 20 less than the number of top students among boys.

Calculating the Number of Girls and Top Students

First, let's calculate the number of girls and top students among them.

Number of Girls (G): We know that girls make up 40% of the class. We can calculate the number of girls using this information.

Number of Top Students Among Girls (OG): We are given that top students make up 25% of the girls. We can calculate the number of top students among girls using this information.

Calculating the Number of Boys and Top Students

Next, we can calculate the number of boys and top students among them.

Number of Boys (B): Since girls make up 40% of the class, boys make up the remaining percentage. We can calculate the number of boys using this information.

Number of Top Students Among Boys (OB): We are given that the number of top students among boys is 20 more than the number of top students among girls. We can calculate the number of top students among boys using this information.

Finding the Total Number of Students

Finally, we can find the total number of students in the class using the information we have calculated.

Total Number of Students (T): The total number of students in the class is the sum of the number of girls and boys.

Let's proceed with the calculations.