An equilateral triangle has sides of length 2 units. A second equilateral triangle is formed having sides that are 150% of the length of the sides of the first triangle. A third equilateral triangle is formed having sides that are 150% of the length of the sides of the second triangle. The process is continued until four equilateral triangles exist. What will be the percent increase in the perimeter from the first triangle to the fourth triangle? Express your answer to the nearest tenth.

mathleteig Nov 17, 2019

#1**+1 **

The side lengths are increased to 2 x 1.5 x 1.5 x 1.5 = 2 (1.5)3 = 6.75

original perimeter = 2 *3 = 6 new largest perimeter = 6.75 x 3 = 20.25

Per cent increase 20.25/6 x 100% = 337.5 % (now look at 1.53 this equals 3.375 )

ElectricPavlov Nov 17, 2019

#3**+1 **

*An equilateral triangle has sides of length 2 units. A second equilateral triangle is formed having sides that are 150% of the length of the sides of the first triangle. A third equilateral triangle is formed having sides that are 150% of the length of the sides of the second triangle. The process is continued until four equilateral triangles exist. What will be the percent increase in the perimeter from the first triangle to the fourth triangle? Express your answer to the nearest tenth.*

Doing this with percents confuses me. Let's get rid of the % signs and say it as follows:

An equilateral triangle has sides of length 2 units. A second equilateral triangle is formed having sides that are 1**.**50 times the length of the sides of the first triangle, and so on.

The second triangle has sides 1**.**5 times the length of the first

And the third triangle has sides 1**.**5 times the length of the second

And the fourth triangle has sides 1**.**5 times the length of the third

So the fourth triangle has sides 1**.**5 x 1**.**5 x 1**.**5 times the length of the first

Do the multiplication, and the fourth triangle has sides 3**.**375 times the length of the first

Change the factor of 3**.**375 back to percent and the percent increase is **337.5 percent**. Stating that the first triangle's sides were 2 units long was a red herring. The question asked for the percent increase

_{.}

Guest Nov 17, 2019

#5**+1 **

**First triangle = 2 units 2nd triangle =1.5 x 2 =3 units. 3rd triangle =3 x 1.5 =4.5 units 4th triangle =4.5 x 1.5 =6.75 units. 6.75 / 2 =3.375 - 1 x 100 =237.5% increase in the perimeter from the first to the 4th triangle.**

Guest Nov 17, 2019

#7**+1 **

Per cents are always kinda tricky

150% of 2 == 3 2nd side length

150% 0f 3 = 4.5

150% 0f 4.5 = 6.75

z% of 2 = 6.75

6.75/2 = 3.375 337.5% OF 2 The INCREASE FROM 2 (6.75-2)/2 = 2.375 = 237.5 %

SO I think the wording is tricky, but the answer looked for is 237.5 %

ElectricPavlov Nov 17, 2019