Periodically, a town water department tests the drinking water of homeowners for
ID: 3306596 • Letter: P
Question
Periodically, a town water department tests the drinking water of homeowners for contaminants such as lead. The lead levels in water specimens collected for a sample of 10 residents of the town are shown.
a. Fill in the following table based on the descriptive statistics generated by MS Excel (round each answer to four decimal places as
needed):
Sample mean
nothing
Sample standard deviation
nothing
Sample variance
nothing
b.
Use the MS Excel Descriptive Statistics to construct a
9999%
confidence interval for the mean lead level in water specimens from the town. NOTE: you will need to look up the critical value on the probability table in the textbook since Excel does not provide this information.
Critical value =
nothing
(Round to three decimal places as needed.)
Confidence Interval:
left parenthesis nothing comma nothing right parenthesis,
(Round to three decimal places as needed.)
c. Interpret the interval in the words of the problem.
The confidence interval means that we are
nothing%
confident that the true
lead level variance
lead level standard deviation
mean lead level
for all the people in
the town
the sample
is in the interval.
d. Discuss the meaning of the phrase,"99%
confident."
The phrase
"99%
confident" means that if many intervals were constructed using the same methods and the same
, then
nothing%
of those intervals would contain the true
population mean
population variance
population standard deviation
sample size
sample mean
sample variance
sample standard deviation
.
Lead left parenthesis mg divided by Upper L right parenthesisLead (mg/L)
1.311.31
3.13.1
00
1.311.31
13.113.1
4.074.07
0.9260.926
4.464.46
0.6190.619
00
Periodically, a town water department tests the drinking water of homeowners for contaminants such as lead. The lead levels in water specimens collected for a sample of 10 residents of the town are shown.
a. Fill in the following table based on the descriptive statistics generated by MS Excel (round each answer to four decimal places as
needed):
Sample mean
nothing
Sample standard deviation
nothing
Sample variance
nothing
b.
Use the MS Excel Descriptive Statistics to construct a
9999%
confidence interval for the mean lead level in water specimens from the town. NOTE: you will need to look up the critical value on the probability table in the textbook since Excel does not provide this information.
Critical value =
nothing
(Round to three decimal places as needed.)
Confidence Interval:
left parenthesis nothing comma nothing right parenthesis,
(Round to three decimal places as needed.)
c. Interpret the interval in the words of the problem.
The confidence interval means that we are
nothing%
confident that the true
lead level variance
lead level standard deviation
mean lead level
for all the people in
the town
the sample
is in the interval.
d. Discuss the meaning of the phrase,"99%
confident."
The phrase
"99%
confident" means that if many intervals were constructed using the same methods and the same
, then
nothing%
of those intervals would contain the true
population mean
population variance
population standard deviation
sample size
sample mean
sample variance
sample standard deviation
.
Lead left parenthesis mg divided by Upper L right parenthesisLead (mg/L)
1.311.31
3.13.1
00
1.311.31
13.113.1
4.074.07
0.9260.926
4.464.46
0.6190.619
00
Explanation / Answer
for above values :
mean =2.8895
std deviation =3.9279
sample variance =15.4286
b)Critical value for 9 degree of freedom =3.2498
Confidence Interval: =-1.1472 ; 6.9262
c)The confidence interval means that we are 99% confident that the true
mean lead level for all the people in the town is in the interval.
d) if many intervals were constructed using the same methods and the same then 99% of those intervals would contain the true population mean
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