Where does all the water go? According to the Environmental Protection Agency (E
ID: 1168979 • Letter: W
Question
Where does all the water go? According to the Environmental Protection Agency (EPA), in a typical wetland environment, 40% of the water is outflow; 50% is seepage; 7% evaporates; and 3% remains as water volume in the ecosystem (Reference: United States Environmental Protection Agency Case Studies Report 832-R-93-005). Chloride compounds as residuals from residential areas are a problem for wetlands. Suppose that in a particular wetland environment the following concentrations (mg/l) of chloride compounds were found: outflow, 58.7; seepage, 72.7; remaining due to evaporation, 28.1; in the water volume, 28.1.
(a) Compute the weighted average of chlorine compound concentration (mg/l) for this ecological system. (Enter your answer to one decimal place.)
mg/l
(b) Suppose the EPA has established an average chlorine compound concentration target of no more than 58 mg/l. Does this wetlands system meet the target standard for chlorine compound concentration?
Yes. The average chlorine compound concentration (mg/l) is too high.
Yes. The average chlorine compound concentration (mg/l) is lower than the target.
No. The average chlorine compound concentration (mg/l) is lower than the target.
No. The average chlorine compound concentration (mg/l) is too high.
Explanation / Answer
a.
Weighted average is as below:
Heads
Concentration (C)
Weights (W)
Weighted average (C× W)
Outflow
58.7
0.40
23.48
Seepage
72.7
0.50
36.35
Evaporate
28.1
0.07
1.967
Remain
28.1
0.03
0.843
1.00
62.64
Answer: The required weighted average is 62.6 mg/l
b.
No. The average is too high.
It should not cross 58 mg/l. But in actual it is 62.6 mg/l.
Answer: The last option is correct.
Heads
Concentration (C)
Weights (W)
Weighted average (C× W)
Outflow
58.7
0.40
23.48
Seepage
72.7
0.50
36.35
Evaporate
28.1
0.07
1.967
Remain
28.1
0.03
0.843
1.00
62.64
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