The original breadth of a rectangular box is 25 cm. The box was then remade in such a way that its length was increased by 30% but the breadth decreased by 20% and the area increased by 100 cm2. What is the length (in cm) of the new box?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 130 .
Let original length = x cm, original breadth = 25 cm
Original area = x × 25 = 25x
New length = x + 30% of x = 1.3x
New breadth = 25 − 20% of 25 = 20 cm
New area = 1.3x × 20 = 26x
Area increased by 100 cm²:
New area − Original area = 26x − 25x = x = 100
⇒ x = 100
New length = 1.3 × 100 = 130 cm