Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site utah-gr.UUCP
Path: utzoo!linus!decvax!decwrl!greipa!pesnta!hplabs!utah-cs!utah-gr!thomas
From: thomas@utah-gr.UUCP (Spencer W. Thomas)
Newsgroups: net.med,net.math
Subject: Re: The Perils of Nutrasweet: digits of precision
Message-ID: <1570@utah-gr.UUCP>
Date: Fri, 23-Aug-85 17:53:50 EDT
Article-I.D.: utah-gr.1570
Posted: Fri Aug 23 17:53:50 1985
Date-Received: Wed, 28-Aug-85 06:01:27 EDT
References: <771@burl.UUCP> <394@petrus.UUCP> <182@steinmetz.UUCP>
Reply-To: thomas@utah-gr.UUCP (Spencer W. Thomas)
Organization: Univ of Utah CS Dept
Lines: 28
Xref: linus net.med:1994 net.math:1831
Summary: 

In article <509@linus.UUCP> meister@linus.UUCP (Philip W. Servita) writes:
(various expletives deleted)
>    GIVEN: a table 3 x 4 meters
>
>    THEN:  that table has an area of 12 meters square. PERIOD.
the number "3" used in a measurement context (rather than 3.0 or 3.000)
means "3 +/- 0.5"  Multiplying out the limit cases, we get that the area
of the table is between 2.5x3.5 = 8.75 and 3.5x4.5 = 15.75 or
approximately 1e1.  Saying "3" instead of "3 +/- 0.5" is a convenient
shorthand.  While mathematically 3x4 is 12, when dealing with
measurements you must ALWAYS consider the precision.  
>
>2) (what the physics and sig figs people SHOULD ask)
>
>    Using a stick ruled only in meters, i measured a table to be about 
>    3 meters wide by 4 meters long. What is its area? (correct answer 
>    about 10 meters square)
This is exactly what a measurement type means when he (or she) says the
table is "3 meters by 4 meters".  Again, it's a shorthand (or jargon)
that you learn to understand when you enter the field (just like Kb and
the like in CS).

-- 
=Spencer   ({ihnp4,decvax}!utah-cs!thomas, thomas@utah-cs.ARPA)
	"To feel at home, stay at home.  A foreign country is not designed
	 to make [one] comfortable.  It's designed to make its own people
	 comfortable."  Clifton Fadiman