airplanes weight and balance doesnt add up...whats the deal?

[jconway2002]

The airplanes weight and balance lists the following:

weight: 1161.2

arm: 30.2

moment: 35069.7

The problem is, if you multiply the weight times arm you get 35068.24. Am I missing something? Why is there a difference between the moment I calculated and the moment listed in the weight and balance sheet of the airplane?

 

[Sac Arrow]

Rounding error. If you back calulate the weight they are pretty close.

 

[MAKG1]

Your arm has three significant figures, and your moment and the W&B moment agree to three figures.

What's the problem?

Arm is calculated, not measured. Do you care about the difference between 30.2 inches and 30.2012 inches? If you want to be that accurate, you'll have to measure your body's CG position with a micrometer....

 

[jconway2002]

Rounding error. If you back calulate the weight they are pretty close.

I thought as much. Thanks for confirming.

 

[Matthew]

if you do the math, 1161.2 * 30.2 = 35068.24 ( what you got )
but 35069.7 / 30.2 = 1161.25 ( what's in the w&b ). That's a difference of 0.05 lb, or less than an ounce.

I suspect it's just a rounding deal when someone typed it up?


edit: D'oh, I need to math faster.