The actual area of a rectangle is 60 Cm^2, but while measuring its length a student

Ques - The actual area of a rectangle is 60 Cm², but while measuring its length a student decreases it by 20% and the breadth increases by 25%. The percentage error in area, calculated by the student is :

A. 5%

B. 25%

C. Can't determined 

D. None of these

Soution - Actual area of rectangle = 60cm²

L×B = 60--------- (1)   (area of rectangle = L×B )

Length decreases = 20%

new length = L - 20% of L

= L - 0.2L

= 0.8L cm

Breadth increases = 25%

new breadth = B + 25% of B

= B + 0.25B

= 1.25B cm

new area = new length ×new breadth

new area = 0.8L × 1.25B

new area = 1 LB

According to equation (1) LB = 60

new area = 1 × LB

new area = 1 × 60

new area = 60cm²

new area = actual area

60cm² = 60cm²

Therefore,

There is no change in area .

Hence,

The correct option is (d) none of these.