Question 3 The observations in the table below are dissolved oxygen contents in

Question

Question 3 The observations in the table below are dissolved oxygen contents in river water. The higher the dissolved oxygen content, the greater the ability of the river to support aquatic life. A pollution control inspector selected 7 specimens of river water above the town and another 5 from below the town. Use a Wilcoxon rank sum procedure to determine whether the readings above town are significantly higher than the readings below town. Use = 5%

3.60

Readings from above town (in parts per million) Readings from below Town (in parts per million)

3.60

3.00 3.80 3.40 3.60 3.10 2.90 3.50 3.20 3.30 3.40 3.70

Explanation / Answer

H0 : There is no significant difference between the dissolved oxygen content in river water above town and in river water below town.

Ha : There is higher dissolved oxygen content in the above town river water than the river water below town.

Here THe rank table is given below.

Here the bold are from Table 1

Sum of ranks for above town = 1 + 4 + 6.5 + 9.5 + 9.5 + 11 + 12 = 53.5

Sum of ranks for below town = 2 + 3 + 5 + 6.5 + 8 = 24.5

here n is not greater than 10 so we cant do normal approximation.

Here Test statistic

W = 53.5

Here at alpha = 0.05, the critical W value = 17

so W > Wcritical so we shallnot reject the null hypothesis so there is not enough evidence to claim that both population mean are different from each other.

Readings from above town (in parts per million) Readings from below Town (in parts per million) Combined order Combined Rank Rank 3.6 3 3.6 2.9 1 3.8 3.4 3.8 3 2 3.6 3.1 3.6 3.1 3 2.9 3.5 2.9 3.2 4 3.2 3.3 3.2 3.3 5 3.4 3.4 3.4 6.5 3.7 3.7 3.4 6.5 3 3.5 8 3.4 3.6 9.5 3.1 3.6 9.5 3.5 3.7 11 3.3 3.8 12

Related Questions

Navigate

• Browse (All)
• Browse Q
• Subjects

---

---

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