RRB Group-D Model Paper 13 with answers for online practice

Given:
Length of the rectangle increased by = 80%
Breadth of the rectangle increased by = 20%
Formula:
Area of the rectangle = Length × Breadth
Calculation:
Let length and breadth of the rectangle be x and y respectively
⇒ Area of the rectangle = xy
New length of the rectangle = x × (180/100) = 1.8x
New breadth of the rectangle = y × (120/100) = 1.2y
⇒ New area of the rectangle = 1.8x × 1.2y = 2.16xy
Area increased by = 2.16xy – xy = 1.16xy
∴ required percent = (1.16xy/xy) × 100 = 116%
Short Trick:
If length and breadth increased by 80% and 20% respectively
⇒ Area increased by = 80 + 20 + (80 × 20)/100 = 100 + 16 = 116%