Challenge Problem: Go to www.cengage.com/chemistry/skoog/fac9, choose Chapter 6, and go to...

Challenge Problem: Go to www.cengage.com/chemistry/skoog/fac9, choose Chapter 6, and go to the Web Works. Find the NIST Statistical ReferenceDatasets site and the Dataset Archives. Click on Analysis of Variance, and find the AtmWtAg data set. Select the two-column formatted data set. The web page contains the atomic mass of silver as presented by L. J. Powell, T. J. Murphy, and J. W. Gramlich, “The Absolute Isotopic Abundance&Atomic Weight of a Reference Sample of Silver”, NBS Journal of Research, 1982, 87, 9–19. The page that you see contains 48 values for the atomic mass of silver, 24 determined by one instrument and 24 determined by another.

(a) We will first import the data. Once you have the data on the screen, click on File/Save As..., and Ag_Atomic_Wtt.dat will appear in the File name blank. Click on Save. Then start Excel, click on File/Open, and be sure that All Files (*.*) is selected in the Files of type: blank. Find Ag_Atomic_Wtt.dat, highlight the file name, and click on Open.After the Test Import Wizard appears, click on Delimited and then Next. In the next window, be sure that only Space is checked, and scroll down to the bottom of the file to be sure that Excel draws vertical lines to separate the two columns of atomic mass data; then click on Finish. The data should then appear in the spreadsheet. The data in the first 60 rows will look a bit disorganized, but beginning in row 61, the atomic mass data should appear in two columns of the spreadsheet. You may have to change the Instrument number labels to correspond to the two columns.

(b) Now, find the mean and standard deviation of the two sets of data. Also determine the coefficient of variation for each data set.

(c) Next, find the pooled standard deviation of the two sets of data, and compare your value to the value for the certified residual standard deviation presented when you click on Certified Values on the NIST Web page. Be sure to increase the displayed number of digits in your spreadsheet so that you can compare all of the digits.

(d) Compare your sum of squares of the deviations from the two means with the NIST value for the certified sum of squares (within instrument). Comment on any differences that you find between your results and the certified values, and suggest possible reasons for the differences.

(e) Compare the mean values for the two sets of data for the atomic mass of silver to the currently accepted value. Assuming the currently accepted value is the true value, determine the absolute error and the relative error in percent.