Posted by Cassie on .
I need to find the volume of a cylinder. Use 3.14 for pi...I think the answer is 24,501.42 m^2...the picture shown is a cylinder with a diameter of 34m and a heigth of 27m
I know how to work these problems out and I got 24,501.42m^2 but the computer is giving me an answer of 24,523.71...please check my answer...thank you

Algebra 
Reiny,
V = πr^2 h
= π (17^2)(27) = 24513.84
using 3.14 for π
V = 4.14(17^2)(27) = 24501.42
you are right! 
Algebra 
Cassie,
You meant to put 3.14 on the secon part...right?

Algebra 
Cassie,
second part I meant....right??

Algebra 
Jeff,
You did the problem correctly. I am not sure how exactly you entered the numbers into the computer for pi, but it looks like with an answer of 24,523.71 the computer used an approzimation for pi based on the fraction 22/7.
22/7 = 3.142857....
If you plug the 22/7 instead of 3.14 you will get what the computer gets... 
Algebra 
Cassie,
Thank you Jeff....

Algebra 
Reiny,
I find it very odd, that the "computer" would use 22/7 for the value of π.
Surely it would have better value than that built in
Even the cheapest calculator will use about 9 decimal places for accuracy.
It looks to me that whatever "input routine" they are using, needs an immediate update to bring it into the 21st century. 
Algebra 
Jeff,
Reiny, Agreed, but that is what it appears to be using. I am guessing it was a software program and not the actual computer using that approximation.
What really irks me about pi is that most people know it is 3.1415....., but have NO idea what it actually represents.... 
Algebra 
Jeff,
BTW Cassie, please please always remember that pi is simply a circle's circumference divided by it's diameter. For every circle, no matter the size...
This is why it shows up in so many formulas for circles, cylinders, cones, etc. 
Algebra 
Cassie,
ok ....thank you