[YAPA] significant figures and averages

[Anthony Barbuto]

I am replying to all  because I want to know if I am correct.
The result of 22.54 for the addition is correct because you go to the hundreths place. Then you divide and you apply to rule for division to the result. But, you go back to the original collected data to establish 3 sigs. So, the result should be expressed as 7.51

Tony

----- Original Message -----
From: Norma Holowach <norma.holowach at neomin.org>
Date: Friday, September 11, 2009 11:12 am
Subject: [YAPA] significant figures and averages
To: YAPA YAPA <yapa at lists.ysu.edu>

>  
> 
> Working with significant figures and averaging several trials can
> lead to some awkward answers. For example if I have the following
> results for the density of a solid:  7.55 g/cm3, 8.10g/cm3, 
> 6.89g/cm3 the total would be 22.54 g/cm3 divided by the 
> three trials and
> appears that there should be 4 significant figures listed for the
> average, 7.513g/cm3.   This does not seem right that 
> the average
> would be written to the thousandths place when the trials only went
> to the hundreth place.  What am I missing here?   
>  Norma Holowach, M.Ed 
>  National Board Certified Teacher 
>  Science Department Chairperson 
>  Lakeview High School 
>  300 Hillman Drive 
>  Cortland, OH 44410 
>  (330)637-4921 
>  "Connecting with nature is an essential part of being 
> alive." 
>  National Geographic. 
>  
> 

Tony Barbuto
Science Teacher
Theodore Roosevelt High School
1400 North Mantua Street
Kent, OH 44240
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