Question

As a part of a study, a chemical plant sampled the amount of chemicals in the soil surrounding their building. Samples were taken in front of the building (sample 1) and samples were taken in the back of the building (sample 2). The results in ppm are listed below. Determine if there is a difference in the amount of chemicals in the soil in the front vs the back of the chemical plant. Perform the five steps of the hypothesis test (assume equal variances).

Sample 1	Sample 2
0	5.5
1.8	3.9
1.5	5.9
0.4	2.6
3.5	6.8
1.7	1.8
3.9	4.5
5.4	2.5
2.5	3.9
2.7	3.9

Answer 1

Null Hypothesis

Alternative Hypothesis

The value of mean and standard deviation for sample 1 and sample 2 is

	Sample 1	Sample 2
Mean
Standard deviation

Under H0, the test statistic is

Degrees of freedom = n1+n2-2 = 18

Significance level

The critical value of t for 18 df at 5% suignificance level is +/-2.101

The P-Value is .0232

Since p value is less than significance level. Reject H0.

Hence , at 5% significance level, we have enough evidence to conclude that there is a difference in the amount of chemicals in the soil in the front vs the back of the chemical plant