The students of a class are made to stand in rows. If 3 students are extra in a row, there would be 1 row less. If 3 students are less in a row, there would be 2 rows more. Find the number of students in the class.

AcademicMathematicsNCERTClass 10

Given:

The students of a class are made to stand in rows. If 3 student are extra in a row, there would be 1 row less. If 3 students are less in a row there would be 2 rows more.

To do:

We have to find the number of students in the class.

Solution:

Let the number of rows be $x$ and the number of students in each row be $y$.

This implies,

Total number of students $=xy$ If 3 student are extra in a row, there would be 1 row less.

$\Rightarrow (x+3)(y-1)=xy$

$xy-x+3y-3=xy$

$x=3y-3$....(i)  If 3 students are less in a row there would be 2 rows more.

$\Rightarrow (x-3)(y+2)=xy$

$xy+2x-3y-6=xy$

$2x=3y+6$

$2(3y-3)=3y+6$      (From (i))

$6y-6=3y+6$

$6y-3y=6+6$

$3y=12$

$y=\frac{12}{3}$

$y=4$

$\Rightarrow x=3(4)-3$      (From (i))

$x=12-3$

$x=9$

$\Rightarrow xy=9\times4=36$

Therefore, the number of students in the class is 36.

raja
Updated on 10-Oct-2022 13:20:04

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