Problem 1.(5pts) Mercury is a toxic element and serves no beneficial physiologic
ID: 3182045 • Letter: P
Question
Problem 1.(5pts)
Mercury is a toxic element and serves no beneficial physiological function in man; a maximum acceptable concentration of 0.001 mg/L (1 µg/L) in drinking water has therefore been established. A researcher pull samples of drinking water from the county X. The results are given in table below.
Position
Mercury µg/L
1
0.80
2
0.67
3
0.88
4
1.06
5
0.98
6
0.85
7
0.90
8
1.01
9
0.84
10
0.81
11
0.76
12
0.90
13
0.84
14
0.67
15
1.01
16
0.87
17
0.94
18
0.94
19
0.94
20
1.07
21
0.96
22
0.80
23
0.80
24
0.76
25
1.09
26
0.87
27
0.82
28
0.89
29
0.85
30
0.95
31
0.97
With confidence of 99.99% determine whether the level of mercury in water in County X is safe.
Position
Mercury µg/L
1
0.80
2
0.67
3
0.88
4
1.06
5
0.98
6
0.85
7
0.90
8
1.01
9
0.84
10
0.81
11
0.76
12
0.90
13
0.84
14
0.67
15
1.01
16
0.87
17
0.94
18
0.94
19
0.94
20
1.07
21
0.96
22
0.80
23
0.80
24
0.76
25
1.09
26
0.87
27
0.82
28
0.89
29
0.85
30
0.95
31
0.97
Explanation / Answer
Below are the null and alternate hypothesis
H0: mu >= 1
H1: mu < 1
test statistics,
t = (0.8871 - 1)/(0.1041/sqrt(31)) = -6.0384
degrees of freedom = 30
p-value < 0.00001
Significance level = 0.0001
As p-value is less than the significance level, reject null hypothesis.
This means given data suggests the water is safe for drinking.
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