Two different analytical methods were used to determine residual chlorine in sewage effluents. Both methods were used on the same samples, but each ca

Ramsey 2021-01-06 Answered
Two different analytical methods were used to determine residual chlorine in sewage effluents. Both methods were used on the same samples, but each came from various locations, with differing amounts of contact time with the effluent. The concentration of Cl in mg//L was determined by the two methods, and the following results were obtained:
Method A:0.39,0.84,1.76,3.35,4.69,7.70,10.52,10.92
Method B:0.36,1.35,2.56,3.92,5.35,8.33,10.70,10.91
(a) What type of t test should be used to compare the two methods and why?
(b) Do the two methods give different results?
(c) Does the conclusion depend on whether the 90%, 95% or 99% confidence levels are used?
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Expert Answer

Roosevelt Houghton
Answered 2021-01-07 Author has 106 answers

Step 1
image
The mean is given by
x=1nx
A)x=5.02125
B)y=5.435
The standard deviation is given by
σ=1n1(xx)2
A)s1=4.2203
B)s1=4.1246
Step 2
a) We will be using an independent two-sample t-test as we are comparing two different populations.
b) The null and alternative hypotheses are
H0:u1=u2
H1:u1u2
The test statistic is given by
t=xys12n1+s22n2
t=5.021255.435(4.2203)28+(4.1246)28
t=0.19831
p - value =0.8446
Since the p-value is greater than 0.05, we fail to reject the null hypothesis and conclude that there is no significant difference between the two methods.

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Answered 2021-09-09

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