Question

EXERCISE 3.2
. Form the pair of linear equations in the following problems, and find their solutions
graphically
(1) 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
() 5 pencils and 7 pens together cost * 50, whereas 7 pencils and 5 pens together
cost 46. Find the cost of one pencil and that of one pen.​

Answer 1

Answer:

) Consider number of boys =x

and number of girls =y.

According to the question,

x+y=10

or, y=10−x ………(i)

y=x+4 ………..(ii)

x 1 2 3

4

y 9 8 7 6

x 1

2 3 4

y 5 6 7 8

Graphical solution : Girls =7, boys =3

(ii) Consider price of a pencil is x

and price of a pen is y.

According to the question,

5x+7y=50.....(i)

7x+5y=46 .….(ii)

x 1 2 3 4

y 7.8 6.4 5 4.2

x 1 2 3 4

y 6.4 5.7 5 4.2

Graphical solution :

Price of a pencil is Rs 3

Price of a pen is Rs 5.

Answer 2

Answer:

Price of pen- RS.5

price of pencil- RS.3