[YAPA] significant figures and averages

[Larry Sherer]

Norma, 

It would seem that since you only had 3 significant figures in each of the original measurements, that the calculated mean/average of 7.513333333...would be rounded and reported as 7.51 g.cm3, or the whole purpose of using significant figures would be lost. 

The other thing that might be necessary if you were reporting these widely spaced data are a box and whisker plot or some other statistical devices that would convey the range of values in the group.  

Larry 

Larry Sherer 


----- Original Message ----- 
From: "Norma Holowach" <norma.holowach at neomin.org> 
To: "YAPA YAPA" <yapa at lists.ysu.edu> 
Sent: Friday, September 11, 2009 11:12:20 AM GMT -05:00 US/Canada Eastern 
Subject: [YAPA] significant figures and averages 



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. 

_______________________________________________ YAPA mailing list YAPA at lists.ysu.edu http://lists.ysu.edu/mailman/listinfo.cgi/yapa-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.ysu.edu/pipermail/yapa/attachments/20090911/166060f5/attachment.htm