Q. 10 students of Class X took part in a Mathematics quiz. If the
number of girls is 4 more than the number of boys,
find the number of boys and girls who took part in the quiz. Solve graphically.
Sol :
Let the number of boys be x and the number of girls be y.
According to the first condition,
x
+
y
=
10
... (i)
According to the second condition,
y
=
x
+
4
... (ii)
x + y = 10
x
y
(x, y)
0
10
(0, 10)
10
0
(10, 0)
y = x + 4
x
y
(x, y)
0
4
(0,4)
4
8
(4,8)
Scale
1 cm = 1 unit on both the axes
Y
Y′
0
X
1
3
2
5
4
7
6
8
9
10
11
1
2
3
4
5
6
7
8
9
10
(0 , 10)
(10 , 0)
x + y = 10
(0 , 4)
(4 , 8)
(3 , 7)
Y= x + 4
3 Boys and 7 Girls took part in quiz.
∴
Total no. of students = 10
For graphical representation we need two solutions of each equation
X′