Probability and Statistics for Engineering and the Sciences
9th Edition
ISBN: 9781305251809
Author: Jay L. Devore
Publisher: Cengage Learning
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Chapter 9, Problem 80SE
Arsenic is a known carcinogen and poison. The standard laboratory procedures for measuring arsenic concentration (mg/L) in water are expensive. Consider the accompanying summary data and Minitab output for comparing a laboratory method to a new relatively quick and inexpensive field method (from the article “Evaluation of a New Field Measurement Method for Arsenic in Drinking Water Samples,” J. of Envir. Engr., 2008: 382–388).
Two-Sample T-Test and CI
| Sample | N | Mean | StDev | SE Mean |
| 1 | 3 | 19. 70 | 1.10 | 0 . 64 |
| 2 | 3 | 10 . 90 | 0 . 60 | 0 .35 |
| Estimate for difference: 8.800 | ||||
| 95% Cl for difference: (6.498, 11.102) | ||||
| T-Test of difference = 0 (vs not =) : | ||||
| T-Value =12.16 P-Value =0.001 DF = 3 | ||||
What conclusion do you draw about the two methods, and why? Interpret the given confidence interval. [Note: One of the article’s authors indicated in private communication that they were unsure why the two methods disagreed.]
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Chapter 9 Solutions
Probability and Statistics for Engineering and the Sciences
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