Question

1.

The Springfield Water Treatment plant is constantly measuring the quality of their drinking water. The level of pH is one item that is measured by them, and the water treatment plant has a target pH of 8.2. In a recent test of 14 samples of water from the treatment plant, they found the following pH levels in their water: 8.6, 8.5, 9.1, 8.4, 8.1, 9.3, 8.8, 8.9, 9.3, 8.0, 8.7, 8.6, 8.7, 9.1 . Also assume that the pH level in the water is approximately normally distributed

a.Create a sketch of the t-distribution for this situation and label the critical value(s). Com- pute your test statistic and label it on your sketch.

b. Compute the p-value of your test statistic using the “pt()” function. Interpret this value with a complete sentence.

c.What is the conclusion of our test? Interpret your results in plain language.

d.Use “t.test(X, alternative = “two.sided”, mu= 8.2)” on R to quickly verify your result from question 3.

Answer 1