The perimeter of a 7-sided figure is 15. If the length of each side of the figure is increased by 2 units, wha

The perimeter of a 7-sided figure is 15. If the length of each side of the figure is increased by 2 units, what is the perimeter of the new figure???


The first time I saw this question, I approached it in a way that got me the wrong answer. This is what I did. I figured that the perimeter is 15, and there are 7 sides, so I divided 15/7 to get something around 2.14 .... (the length of each side I guess)

then I multiplied the 2.14 by 9 (sides) to get something around 19. That was not the right answer, and I saw how to solve it, but did not understand it. The correct answer was 29

Here is the explanation: The perimeter is the sum of the lengths of all the sides. Since each of the seven sides is to be increased by 2, there will be a total increase of 14 in the perimeter. The original perimeter, 15, plus the increase, 14, gives the new perimeter, 29.



Im just wondering why does my method get the wrong answer, it seems reasonable

You made the number of sides increase by 2, when it said that the length of each side increased by 2. So if each length increased by 2, the perimeters would go up by 7*2 giving 15+14=29.

You said "I multiplied the 2.14 by 9..."

Rather, (2.14 + 2) (7) = 28.98

arpz is right

its a 7 sided figure with perimeter = 15 units.

if each side is increased by 2 units, total increase in Perimeter will be 2*7 = 14 units.

new perimeter = 14+15

= 29 units.


you are right.

why did you posted this q? are you asking or telling?

anyways, your approach was lengthy but not wrong.

one side = 15/7 = 2.14 units is o.k.

but after that you X'd by 9 when you should have done so by 7.

then

7*(2.14+2)

7 * 4.14 = 28.98 units

which is almost same as 29