Question

В начале учебного года в 10 классе, в котором девочки состовляли 60 %, пришли новички- 3 девочек и 2 мальчика. Сколько процентов составляют девочки в новом составе класса

Answer 1

Было:
Всего   100 %    -  Y чел. 
Девочки  60%    - 0.6*Y  чел.   (60%  = 60/100 = 0,6)

Стало:
Всего  100%  -  (Y + 3 + 2) чел.
Девочки D %   -  (0.6Y + 3)  чел.

D =  100*(0.6Y + 3)  /  (Y+3+2)
D =   (60Y + 300)  / (Y + 5)  =  60*(Y +5)  / (Y +5)
D =  60 %

Ответ:  60 %  составляют девочки в новом составе класса.

Answer 2

Calculation of the Percentage of Girls in the New Class

To calculate the percentage of girls in the new class, we need to determine the total number of students in the class after the new students have arrived.

Given: - At the beginning of the school year, girls constituted 60% of the class. - 3 new girls and 2 new boys joined the class.

To calculate the total number of students in the new class, we can use the following formula:

Total number of students = Number of girls + Number of boys

Let's calculate the total number of students in the new class:

Number of girls in the new class = Number of girls in the original class + Number of new girls = 60% + 3 girls

Number of boys in the new class = Number of boys in the original class + Number of new boys = 40% + 2 boys

Now, let's calculate the percentage of girls in the new class:

Percentage of girls in the new class = (Number of girls in the new class / Total number of students in the new class) * 100

Calculation:

Number of girls in the new class = 60% + 3 girls = 63 girls

Number of boys in the new class = 40% + 2 boys = 42 boys

Total number of students in the new class = Number of girls in the new class + Number of boys in the new class = 63 girls + 42 boys = 105 students

Percentage of girls in the new class = (63 girls / 105 students) * 100 = 60%

Therefore, the percentage of girls in the new class is 60%.