Question
Form the pair of linear equations in the following problems, and find their solution graphically:
10 students of class X took part in 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.

Answer

Let the number of girls and boys in the class be x and y respectively.
According to the given conditions, we have,
x + y = 10
x - y = 4
x + y = 10
⇒ x = 10 - y
Three solutions of this equations can be written in a table as follows,
x
4
5
6
y
6
5
4
x - y = 4
⇒ x = 4 + y
Three solutions of this equation can be written in a table as follows.
x
5
4
3
y
1
0
-1
The graphical representation is as follows.

From the graph, it can be observes that the two lines intersect each other at the point (7, 3). So. x = 7 and y = 3. Thus the number of girls and boys in the class are 7 and 3 respectively.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Two customers are visiting a particular shop in the same week (Monday to Saturday). Each is equally likely to visit the shop on any one day as on another. What is the probability that both will visit the shop on:
  1. The same day?
  2. Different days?
  3. Consecutive days?
A bucket made up of a metal sheet is in the form of frustum of a cone. Its depth is $24\ cm$ and the diameters of the top and bottom are $30\ cm$ and $10\ cm$, respectively. Find the cost of completely filling the bucket with milk at the rate of $Rs. 20$ per litre and the cost of metal sheet used if it costs $Rs.\ 10\ per\ 100cm^2.$
$\big[\text{Use }\pi=3.14\big]$
In a tree plantation programme, the number of trees planted by students of different classes is given in the following table. Draw a pie diagram showing the information.
Draw two concentric circles of radii $3\ cm$ and $5\ cm$. Construct a tangent to smaller circle from a point on the larger circle. Also measure its length.
Two coins are tossed simultaneously. Write the sample space (S) and number
of sample points n(S). Also write the following events in the set form and write
the number of sample points in each event.
(i) Condition for event A : to get at least one tail.
(ii) Condition for event B : to get only one head.
(iii) Condition for event C : to get at most one tail.
(iv) Condition for event D : to get no head.
What length of a solid cylinder 2cm in diameter must be taken to recast into a hollow cylinder of length 16cm, external diameter 20 cm and thickness 2.5mm?
The numerator of a fraction is $3$ less than its denominator. If 1 is added to the denominator, the fraction is decreased by $\frac{1}{15}.$ Find the fraction.
Solve the following quadratic equations by factorization:
$4\sqrt{3}\text{x}^2+5\text{x}-2\sqrt{3}=0$
A container, open at the top and made up of metal sheet, is in the form of a frustum of a cone of height $16\ cm$ with diameters of its lower and upper ends as $16\ cm$ and $40\ cm$, respectively. Find the cost of metal sheet used to make the container, if it costs $₹ 10$ per $100\ cm^2.$
Form the pair of linear equations in the following problems, and find their solution graphically:
5 pencils and 7 pens together cost Rs. 50, whereas 7 pencils and 5 pens together cost Rs. 46. Find the cost of one pencil and a pen.