N l;l i XV11 



Is, milli -s liable to error by tin- 



-litution <t' - 'Mimas to mark oif the groups 



tse of a decimal l'ra< 

 Thus write 0.4612 rather 

 than 0.46 12, and 6.382 ratlin than 6.38 2. 



EXAMPLES. 



Example 1. Suppose that a tinal result w as 298549. o.ioper 



::;it its uncertainty or deviation-measure <r estimated 



paize xlii) was o.io per eeiit. To how many }.'. 



,;d it be : o.i per cent of the number is o.ooi x 300000=300. 



the last ' rtainty in the 



v, two uncertain places should be : The 



;ld In- written 298550. 0.10 : 



; 5 0.0062. '1'h is would be an incorrect 



0.0062 shows that the result is uncertain in the third and 



ii. and then fiv in all subsequent decimal places.* The tit'th and sixth 



'icant liirmvs are thus unreliable, so that the seventh and eighth 



. and should. thercf"iv. i ;. W- should 



i6 our jud. to whether the result >huld then be 



writ- 



47. 58 24 0.00 62 or 47.582 0.006, 



: -tainty in the fifth i>lace is lartre. The more common 



In this example the uncertainty is : 0.0002/47. = o.oooi.;. 

 0.013 per cent. It iniirht. tln-ivi'ure. have been i-xi'iTssed as 13 par: 

 100,000, or 0.013 per cent instead of as 0.0062 units. It is aiv csaed 



in t! 'inantity H I when din 



Example 2. Desired with an aceurae-. ;lie volume of a riu'ht 



vlinder whose radi' Inches, ami leimth ' 



multiplication 



ml all Mrps ,-hould In- carrioi 

 -uld have 

 1 ;.i ;j - .' ; ; x 12.65 1 4S 1 - 



t 0.0062, or whatever may be iu value, ta the " average devia- 



Ue average ainnutit i>\ 



niiil.'irly obt \ fiillrr 



\\ith tin* average 



