Question

The water supply for two cities is measured for contaminants. On 16 different days the contamination level for the water from city A was 17 parts per million on average with a standard deviation of 4.2 parts per million. The same data was collected on 14 different days for city B. The average contamination level was 11 parts per million and the standard deviation was 5 parts per million. Use 25 for degrees of freedom. At the 5% significance level is there evidence the mean contamination level for city A is higher than city B?

12. What kind of test is this?

(a) Right-tail

(b) Left-Tail

(c) Two-tail

13. We reject the null hypothesis if

(a) The test statistic is less than -1.72

(b) The test statistic is greater than 2.07

(c) The test statistic is less than -1.71

(d) The test statistic is greater than 1.71

14. The value of the test statistic is (a) -2.86

(b) 2.86

(c) 3.53

(d) 3.79

15. The conclusion is

(a) We accept the null hypothesis

(b) We have evidence for the alternative hypothesis

(c) We may have a Type II error

(d) We do not have evidence for the alternative hypothesis

Answer 1