Question

20. The sides of a rectangle are 40 cm by 30 cm. If each side is increased by 10%, find the
percentage increase in the area.​

Answer 1

Answer:9% increase

Step-by-step explanation:

Rectangle Length=40 cm

Rectangle Breath=30 cm

Area=40×30

Area=1200 cm²

Let Length Increase by 10 %

=40×10%

=40×10/100

=4

40+4

=44 cm

Now Length=44 cm

Breath=30 cm

Area=44×30

=1320 cm ²

Increase in area

=1320- 1200

=120

Percentage=120/1320×100

=9.09 %

Aproxx=9% increase

Answer 2

Answer:

increase in area =21%

Step-by-step explanation:

length, l=40cm

breadth, b=30cm

intitial area=l x b= 40 x 30 = 1200$cm^{2}$

new length= 40 + 10% of 40= 40 + 4=44cm

new breadth= 30 + 10% of 30= 33cm

new area= l x b = 44 x 33 =1452$cm^{2}$

increase in area= new area - initial area = 1452 - 1200 = 252$cm^{2}$

% increase in area= $\frac{increase in area}{initial area} X100 = \frac{252}{1200} X100=21$ %