MATH 2300

046

Fall 2011
HOMEWORK #8
Name___________________________________
Due on 15
th
November
MULTIPLE CHOICE.
Choose the one alternative that best completes the statement or answers the question.
Provide an appropriate response.
1.
A good estimator of a parameter has which of the following properties?
I)
The standard error of the estimator is small.
II)
The estimator is unbiased.
III)
The estimator has a high confidence level.
A.
all of these
B.
both I and II
C.
II only
D.
I only
E.
III only
2.
In monitoring the levels of lead in the air after an explosion at a battery factory, it is found that the amounts of lead (in
ug/m
3
) over a 6 day period had a mean of 1.54 and a standard error of 1.91. Construct a 95% confidence interval for the
population mean.
A.
(

2.2, 5.28)
B.
(

4.11, 7.19)
C.
none of these
D.
(

3.37, 6.45)
E.
(

1.60, 4.68)
3.
A 90% confidence interval for the mean percentage of airline reservations being canceled on the day of the flight is
(1.3%, 5.1%). What is the point estimate of the mean percentage of reservations that are canceled on the day of the
flight?
A) 3.20%
B) 3.80%
C) 2.55%
D) 1.90%
E) 5.10%
Select the most appropriate answer.
4.
In an effort to monitor the level of lead in the air after an explosion at a battery factory, the following lead readings
were taken for 6 days following the explosion (in
ug/m
3
). What is the point estimate for the population mean lead
level in the air over the 6 days following the explosion?
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
5.40
1.10
0.42
0.73
0.48
1.10
A) 2.91
B) 0.73
C) 1.54
D) 0.50
E) 0.42
Use the given degree of confidence and sample data to construct a confidence interval for the population proportion.
5.
Of 346 items tested, 12 are found to be defective. Construct a 98% confidence interval to estimate the proportion of all
such items that are defective.
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 Fall '11
 ABEYSUNDARA
 Statistics, Normal Distribution, Standard Deviation

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