Question

In a P.T. display, 480 students are arranged in rows and columns. If there are 4 more students in each row than the number of rows, find the number of students in each row.

Answer 1

Let the number of rows be x

So, the number of students in each row = x + 4

Given, total students = 480

⇒ x(x + 4) = 480

⇒ x² + 4x = 480

⇒ x² + 4x − 480 = 0

⇒ x² + 24x − 20x − 480 = 0

⇒ x(x + 24) −20(x + 24) = 0

⇒ (x − 20)(x + 24) = 0

⇒ x − 20 = 0 or x + 24 = 0

⇒ x = 20 or x = −24

Since number of rows cannot be negative hence, x ≠ -24.

If x = 20, x + 4 = 24.

Hence, the number of students in each row are 24.