Percentage error (1 Viewer)

[[trent]]

Hi,

I'm feeling really stupid right about now because I can't get my head around how to do percentage error.

The question is: Christine measured the length of her room to be 15.2 meters. What is the percentage error (2 d.p)

I know the range of error is 15.25 - 15.15...so .1

where do i go from there?!?

Thanks!!!

 

[Dr_Doom]

Hi,

I'm feeling really stupid right about now because I can't get my head around how to do percentage error.

The question is: Christine measured the length of her room to be 15.2 meters. What is the percentage error (2 d.p)

I know the range of error is 15.25 - 15.15...so .1

where do i go from there?!?

Thanks!!!

Percentage error = absolute error / measurement x 100

absolute error = 1/2 the precision

precision = lowest unit (in this case 0.1 m)

so absolute error is 0.05 m

therefore:

Percentage error = 0.05 / 15.2 X 100

xD

 

[PC]

Because Christine measured her room and got a measurement of 15.2 metres, you have to assume that measurements can be made to an accuracy of at least 1 decimal place. So this is basically the precision of the measuring device.

Precision = 0.1 m

Then as Dr Doom said,

Absolute error = 1/2 x Precision
= 1/2 x 0.1
= 0.05 m

Percentage = Abs Error/Measurement x 100/1
= 0.05/15.2 x 100/1
= 0.3289473684
~ 0.33%

Limits = Measurement � Abs Error
= 15.2 � 0.05

That's where you get your range from.

------------
Damn PCs. Those question marks are supposed to be plus/minus signs. I can type them on my Mac. When are PCs going to catch up!

 

[[trent]]

thanks!!