1.

The length of a room floor exceeds its breadth by 20 m. The area of the floor remains unaltered when the length is decreased by 10 m and the breadth is increased by 5 m. The area of the floor is :1. 280 m22. 250 m23. 300 m24. 325 m2

Answer» Correct Answer - Option 3 : 300 m2

Given:

The length of a room floor exceeds its breadth by 20 m. The area of the floor remains unaltered when the length is decreased by 10 m and the breadth is increased by 5 m

Concept used:

Area of Rectangle = Length × Breadth

Calculation:

Let the breadth of the floor be x m.

Length = (x + 20) meter

The area of the floor = Length × Breadth 

Area of the floor = (x + 20) x m2

According to the question

Length is decreased by 10 m = (x + 20 - 10) = (x + 10) m

Breadth is increased by 5 m = (x + 5) m

⇒ (x + 10) (x + 5) = x (x + 20)

⇒ x2 + 15x + 50 = x2 + 20x

⇒ 5x = 50

⇒ x = 10 meter

Length of the floor = x + 20 = 30 m

Area of the floor = 30 × 10

∴ Area of the floor = 300 m2 


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