Question No.15
The area of a rectangle is 320 m2. If length is decreased
by 20% and breadth is increased by 25%, then the area
of new rectangle (in m2) is
320
А
160
B
640
C
270
D
Answers
Answer:
320 m²
Explanation:
Let the length be 'a' and breadth be 'b'.
Original area = length * breadth
=> a * b = 320 m²
=> ab = 320 m²
Then, length is decreased by 20%:
New length = a - 20% of a = a(1 - 20%)
New length = a(1 - 0.2) = 0.8 a
Breadth is increased by 25%:
New breadth = b(1 + 25%) = b(1 + 0.25)
New breadth = b(1.25) = 1.25 b
Therefore,
New area = (0.8)a * (1.25)b = (0.8*1.25)ab
New area = 1*ab = 1 * 320 m² = 320 m²
320 m²
Explanation:
Let the length be 'a' and breadth be 'b'.
Original area = length * breadth
=> a * b = 320 m²
=> ab = 320 m²
Then, length is decreased by 20%:
New length = a - 20% of a = a(1 - 20%)
New length = a(1 - 0.2) = 0.8 a
Breadth is increased by 25%:
New breadth = b(1 + 25%) = b(1 + 0.25)
New breadth = b(1.25) = 1.25 b
Therefore,
New area = (0.8)a * (1.25)b = (0.8*1.25)ab
New area = 1*ab = 1 * 320 m² = 320 m²