3. [Kangaroo Grey 2004 Q7] Maija has a rectangular patio in her garden. She decides to make the patio
larger by increasing both its length and width by
10%. What is the percentage increase in the area
of the patio?

21 % increase

Step-by-step explanation:

Lets imagine the sides of the rectangle are 100 & 200 cms.

The area would be 100 x 200 = 20000cm^2

If we added 10% onto each side, the sides would now be 110 & 220 cms.

The area would be 110 x 220 = 24200cm^2

We can now find percentage change:

= 21/100 = 21% increase.

The reason we can just pick random values of sides to do this question with is because we worked out percentage change, which will be the same no matter the proportion of the sides.

Hope this helped! Let me know if you have any questions :)