An outside circular ring has a circumference of 200 cm. What is the circumference of an inner ring which is 25 cm shorter in radius? Both circles have the same center.

Question

anonymous · Answer

attachment

anonymous · Answer

the circumference of any circle is C=2*pi*radius

since the outside circle circumference is 200, then
200 = 2*pi*radius ---> radius = 200/(2*pi) = 100/pi

that's the radius of the bigger circle.  Since the inner ring's radius is 25 cm shorter, then its radius is (100/pi - 25).  Now you can find the circumference of the inner circle by plugging this into the circumference formula.

anonymous · Answer

wow thanks dude i was finding a way to solve it bravo

anonymous · Answer

I got 38.7

anonymous · Answer

But my answer choices are 43.0 cm
		
50.0 cm
		
74.4 cm
		
96.1 cm

anonymous · Answer

make sure you put it in your calculator correctly because the answer is one of those choices...:)

anonymous · Answer

Now on a different calculator I got 6.8 -_-

anonymous · Answer

@CourtneyMichelle , try again..

anonymous · Answer

what kind of calculator u using?

anonymous · Answer

I did, 6.8 again..

anonymous · Answer

At first, just a cheap hand held one. Now the one on my comp

anonymous · Answer

answer is 42.72 
43

anonymous · Answer

let's do it this way then with your cheap calculator..

anonymous · Answer

Thaank you @annas!

anonymous · Answer

@annas , yess

anonymous · Answer

@dpaInc you can still show me how to do it though if you'd like. On my cheap calculator. Because I'm obviously doing something wrong

anonymous · Answer

ok...

anonymous · Answer

press
100/3.14-25=
x3.14x2

that's the sequence of buttons to press on your walmart calculator.

anonymous · Answer

:)

anonymous · Answer

hope that works... :)

anonymous · Answer

welcome @CourtneyMichelle