destroyer QR # 113

[prsndwg]

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This is the easiest looking Q from 2009 Destroyer QR # 113.

Q:There is a rectangle 20*10 and it says if we increase the sides by 20%, how much does the area increases in %?

Thanks

 

[Streetwolf]

This is the easiest looking Q from 2009 Destroyer QR # 113.

Q:There is a rectangle 20*10 and it says if we increase the sides by 20%, how much does the area increases in %?

Thanks

Each side is increase * 1.20 (WHY?) so the area increases 1.20*1.20 = 1.44. Increase of 44%.

If you just did it out you'd get 20 increased by 20% = 24 and 10 increased by 20% = 12. So 24*12 = 288. This is 88 units^2 bigger than 200 which is a 44% increase.

 

[prsndwg]

Thanks for your help. I do get the second solution but still confused with the 1st one.. *1.20.. how is that?

Each side is increase * 1.20 (WHY?) so the area increases 1.20*1.20 = 1.44. Increase of 44%.

If you just did it out you'd get 20 increased by 20% = 24 and 10 increased by 20% = 12. So 24*12 = 288. This is 88 units^2 bigger than 200 which is a 44% increase.

 

[Streetwolf]

Thanks for your help. I do get the second solution but still confused with the 1st one.. *1.20.. how is that?

Each side increases by 20%...

If one side is 'x' units then it increases by (0.20 * x). So the new length is:

x + (0.20x) = 1.20*x

The number 1.20 can be multiplied to all the sides. When you have sides 'x' and 'y', they both are multiplied by 1.20.

1.20x and 1.20y.

The area is xy so the NEW area is 1.20x * 1.20y = 1.44(xy).

So in the end, the old area (xy) is multiplied by 1.44 to get the new area. This is an increase of 44% over the old area.