1.

If the length of rectangle is decreased by 25% and its breadth is increased by 30% then by how much percent its area is increased or decreased?1). 2.5% increased2). 2.5% decreased3). 5% increased4). 5% decreased

Answer»

AREA of rectangle = LENGTH × BREADTH

Let Length of rectangle be a and breadth be b

ORIGINAL area = a × b = AB

New area = (a – 25% of a) × (b + 30% of b)

⇒ New area = 0.75a × 1.3b

⇒ New area = 0.975ab

? 0.975ab < ab, area has decreased

Percent decrease in area = (Original area - New area) × 100/ Original area

⇒ Percent decrease = (ab - 0.975ab) × 100/ab

⇒ Percent decrease = 0.025 × 100 = 2.5%.


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