Question

An environmental scientist developed a new analytical method for the determination of cadmium (Cd2+) in mussels. To validate the method, the researcher measured the Cd2* concentration in standard reference material (SRM) 2976 that is known to contain 0.82 ± 0.16 ppm Cd24. Five replicate measurements of the SRM were obtained using the new method, giving values of 0.794, 0.763, 0.821, 0.835, and 0.768 ppm Cd2+. Calculate the mean (x), standard deviation (s,x), and the 95% confidence interval. A list of t values can be found in the Student's t table. ppm ppm 95% confidence interval: + ppm Does the new method give a result that differs from the known result of the SRM at the 95% confidence level? yes no O O

Answer 1

Mean(oa) i=1 o794 0.763 to83)+035+076 0.7962 PPm Standand daviation(s) 11-12 lo.794-072(-76-0.7068103 -02) NwwYN 4.84X1- 4.0228 Xlo-3 00281 Sx0.0384

Confidence Inteaval bayd on mean andy ZFX= Jh 14 is the -valu forom the table for partiula conf dnre Iutoval mean Sx Standand doviation humber of observation Confidence iterval .282 1645 307 1960 g5/o 11.97. 3-394 0.7962 t960 Xo.0304 J5 0.7962 土 o. 0249 - 0.0249 PPm 95% Confidince Tntrwal Yés
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