Researchers wanted to compare the effectiveness of a water softener used with a filtering process with a water softener used without filtering. Ninety

Jaya Legge 2020-10-23 Answered
Researchers wanted to compare the effectiveness of a water softener used with a filtering process with a water softener used without filtering. Ninety locations were randomly divided into two groups of equal size. Group A locations used a water softener and the filtering process, while group B used only the water softener. At the end of three months, a water sample was tested at each location for its level of softness. (Water softness was measured on a scale of 1 to 5, with 5 being the softest water.) The results were as follows: Group A (water softener and filtering) x1=2.1
s1=0.7 Group B (water softener only) x2=1.7
s2=0.4 Determine, at the 90% confidence level, whether there is a difference between the two types of treatments.
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stuth1
Answered 2020-10-24 Author has 97 answers

Group A x1=2.1
s1=0.7
n1=45 Group B x2=1.7
s2=0.4
n2=45 S.E.=(0.7)245+(0.4)245=0.120
d=x1x2=2.11.7=0.4
tcnc(at 0.10losand902df)=1.65
C.I.=d±tcncS.E.
=0.4±1.65(0.120)
=0.4±0.198
C.I.=(0.202,0.598)

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