Posted by **Laruen** on Sunday, April 15, 2012 at 6:14pm.

19. The circumference of the circle below is 25.12 centimeters

***** There is a circle and then there is a line and written radius

C = 2(pi)r

Which is the best estimate for the length of the radius of the circle?

a) 3 cm

b) 4 cm

c) 8 cm

d) 16 cm

please help i tried to solve this problem and I'm struggling (I'm NOT lying)

but i think the answer is b idk ..... I'm not guessing thought

I know haft of 25.12 is 12.56.

Please help

thank you

- Math 7 - NYS Math Exam Review Help! -
**Ms. Sue**, Sunday, April 15, 2012 at 6:18pm
The formula for the circumference of a circle is:

C = pi * 2r

25.12 = 3.14 * 2r

25.12/3.14 = 2r

8 = 2r

8/2 = r

4 = r

- Math 7 - NYS Math Exam Review Help! -
**Bosnian**, Sunday, April 15, 2012 at 6:19pm
pi = 3.14

2 pi = 6.28

C = 2 r pi

25.12 = 2 r pi Divide both sides by 2 pi

25.12 / 2 pi = r

r = 25.12 / 2 pi

r = 25.12 / 6.28

r = 4 cm

- Math 7 - NYS Math Exam Review Help! -
**Laruen**, Sunday, April 15, 2012 at 6:24pm
Thank You Ms. Sue! :)

Now I understand because I didn't learn this yet in math since we are behind in our curriculum. I'm going to rewrite this so that I way I can use this to study for the exam. I'm going to post more problems (don' worry not too much). I left some geometry questions (about 2) and other problems that I need help with (don't worry it's about 4 more problems or 3 that I'm going to post). Some questions are homework checks to see if I'm correct.

thanks again :)

- Math 7 - NYS Math Exam Review Help! -
**Laruen**, Sunday, April 15, 2012 at 6:29pm
thanks Bosnian

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