I just have a few questions to clairify about my standard deviation and uncertai

Question

I just have a few questions to clairify about my standard deviation and uncertainty as well as the % uncertainty.

1. This has to do with the thickness of a quater that was measured. My average thickness in cm is 0.10cm and I calculated a standard deviation of 0.016 cm because the teacher wants 2 sig figs. when calculating the uncertainty the formula says +-2standard deviation so does that mean that i multiply?! I put 0.016 +-0.20 cm for my uncertainty with 1.2 x 10^3 % as my % uncertainty. ( I had 0.10, 0.11, 0.10 and 0.10 as my four measurements with a ruler). Did I do this corrctly? I just want to make sure I know what I am doing when test time comes around!

Please explain your answers if I am wrong so that I am able to understand what I have to do.

Explanation / Answer

since u have taken the multiple measurement approach we need to follow these steps

first calculate the average = 0.10+.10+.11+.10/4 = 0.1025

now calculate the varience in each case

1- .10-.1025 = - .0025

2- .10-.1025= - .0025

3- .11 -.1025=.0075

4- .10 -1.025 =- .0025

now add up the squares of these differences = .00005625

and take average = .0000140625

then take sqrt of it = .00375

this is the standard deviation and the answer is expressed as .1025 +- .0038

so u made a mistake in the calculation of varience i think :)

have a nice day and for multiple methods of finding standard deviation go throught this link : http://www.wikihow.com/Calculate-Uncertainty

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects