Предмет: Математика, автор: aibar007

В двух класах 6 А и 6 Б 82 ученика, Известно что мальчиков поровну, Мальчики в 6 А   

3/5 от всего класса , а мальчики 6 Б  4/7 всего класса, Сколько учеников и з этих классов, 

Ответы

Автор ответа: turisha
0

Из условия известно, что : В двух классах 6 "А" и 6 "Б" вместе 82 ученика.

A+B=82.

A=X1+Y (где X1 количество мальчиков ,а Y количество девочек),соответственно 

B=X2+Z снова X2 т.к. Известно,что мальчиков в этих классах поровну

(x1+y)+(x2+z)=82

x1=x2

x1=3(x+y)/5 (т.к. в А классе мальчиков 3/5 от всего класса)

5X1=3x1+3y

y=2x1/3

 

x2=(x2+z)*4/7

7x2=4x2+z4

z=3x2/4

 

Дальше подставляем в (x1+y)+(x2+z)=82 полученные значения y и z.

получаем что x =24

т.е.мальчиков в каждом классе 24.

 

48+x+y=82

x+y=34

дальше в классе A девочек: y=(24+y)*2/5

y=16 девочек

 

значит в а классе A -  24+16 детей

а в классе Б 42 человека

 

Мальчики в 6"А" классе составляют 3/5 учащихся всего класса

значит девочек 2/5.ТАк же со вторым классом.

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