Analytical Chem istry - DePauw University

Chapter 4 Evaluating Analytical Data89243−250z lower= =−14.5and the deviation for the upper limit is262−250z upper= =+ 24 .5Using the table in Appendix 3, we find that the percentage of tablets withless than 243 mg of aspirin is 8.08%, and the percentage of tablets withmore than 262 mg of aspirin is 0.82%. Therefore, the percentage of tabletscontaining between 243 and 262 mg of aspirin is100.00% - 8.08% - 0.82 % = 91.10%Figure 4.9 shows the distribution of aspiring in the tablets, with the areain blue showing the percentage of tablets containing between 243 mg and262 mg of aspirin.Practice Exercise 4.5What percentage of aspirin tablets will contain between 240 mg and 245mg of aspirin if the population’s mean is 250 mg and the population’sstandard deviation is 5 mg.Click here to review your answer to this exercise.8.08%0.82%230 240 250 260 270Aspirin (mg)91.10% Figure 4.9 Normal distributionfor the population of aspirin tabletsin Example 4.11. The population’smean and standard deviationare 250 mg and 5 mg, respectively.The shaded area shows the percentageof tablets containing between243 mg and 262 mg of aspirin.