#### Jakotheshadows

##### New member

- Joined
- Jun 29, 2008

- Messages
- 47

First, I use the circumference to find the radius. since C = 2*pi*r, 84 = 2*pi*r, 42 = pi * r, then r = 42 / pi..

a) dr = .5, A = 4*pi*r^2, dA = 8*pi*(42/pi)*.5 = 168 cm squared maximum error.

total surface area = 2245.99 cm squared = A. dA / A = .07 or 7%

b) V = (4/3)*pi*r^3, dV = (4*pi*(42/pi)^2) *.5 = 1122.99 cm cubed maximum error.

total volume = 10008.91 cm cubed = V. dV / V = .11 or 11%

The answers in the appendix give:

for a) 27 cm squared max, .012 relative

for b) 179 cm cubed max, .018 relative

Where is my error?