Arsenic is a chemical element that occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. The main use of metallic arsenic is for strengthening alloys of copper and lead. Unfortunately, arsenic occurs in some ground water. In large quantities it is toxic for multicellular life. A mean arsenic level of 8 particles per billion (ppb) is considered safe for agricultural use. A well in Texas is used to water cotton crops. This well is tested regularly for arsenic. A random sample 37 tests gave a sample mean of 7.2 ppb arsenic with standard deviation of 1.9 ppb. Assume that arsenic levels are normally distributed. We are to use the sample data and test if mean arsenic level in the well in question is less than 8 ppb. a. Test statistic is b. The ? − value of the test is c. At the significance level calculated in part c), we conclude that mean arsenic level in the well is
Contingency Table
A contingency table can be defined as the visual representation of the relationship between two or more categorical variables that can be evaluated and registered. It is a categorical version of the scatterplot, which is used to investigate the linear relationship between two variables. A contingency table is indeed a type of frequency distribution table that displays two variables at the same time.
Binomial Distribution
Binomial is an algebraic expression of the sum or the difference of two terms. Before knowing about binomial distribution, we must know about the binomial theorem.
Arsenic is a chemical element that occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. The main use of metallic arsenic is for strengthening alloys of copper and lead. Unfortunately, arsenic occurs in some ground water. In large quantities it is toxic for multicellular life. A
a. Test statistic is
b. The ? − value of the test is
c. At the significance level calculated in part c), we conclude that mean arsenic level in the
well is
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