Question 2-1 (10 points). Several soil samples were collected at two different l

Question

Question 2-1 (10 points). Several soil samples were collected at two different locations surrounding arn abandoned mine and analyzed for total concentrations of arsenic (As). For each sample, As in soil was extracted with a strong acid and the extract analyzed using flame atomic spectrometry. The obtained data are tabulated below Number of samples collectedMeasured total concentrations of arsenic in each sample expressed in mg/kg 2.3 0.9 2.2 0.5 0.9 Sampling Locations per sampling area (n) 3 5 4 2.2 1.1 2.3 1.0 1.9 1.6 2.6 0.6 1.3 2.1 0.7 1.2 0.4 4 Show vour work: 1. 2. 3. 4. Determine the overall mean of all measurements Calculate the corresponding standard deviation Calculate the pooled estimate of the standard deviation of the method Which of the above areas show mean arsenic concentrations which are not significantly different from each other at 95% confidence level, therefore, indicating a similar pattern of contamination?

Explanation / Answer

(1) overall mean=29.6/21=1.4095

(2) sample variance=s2=sum(xi-x-)2/(n-1)=9.0181/(21-1)=0.4509

sample standard deviation=s=sqrt(0.4509)=0.6715

(3) pooled variance=sum((ni-1)si2/(sum(ni-1))=5.98/16=0.3738

and pooled standard deviation=sqrt(pooled variance)=sqrt(0.3738)=0.6114

(4) here level of significance=alpha=0.05=1-confidence level=1-0.95

using ms-excel one way anova showed there is not siginifiant difference of mean arsenic concentration as p-value of the between group is more than alpha=0.05

sum= 29.6 n= 21 mean=sum/n= 1.4095

Related Questions

Navigate

• Browse (All)
• Browse Q
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.