You are curious about the average number of yards Matthew
Stafford throws for each game for the Detroit Lions. You randomly
select 23 games and see that the average yards per game is 344.5
with a standard deviation of 27.8 yards. You want to create a 95%
confidence interval for the true average number of yards per game
he throws. What is the margin of error for this estimate?
Question 1 options:
Question 2 (1 point)
A company seeks to employ a new public relations manager. The
hiring committee surveys 15 public relations managers and finds the
average salary is $97785.415 with standard deviation of $1764.941.
What is the 95% confidence interval for the true average public
relations manager salary?
Question 2 options:
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1)
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( 96814.306 , 98756.524 ) |
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2)
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( -96808.023 , 98762.807 ) |
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3)
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( 97783.27 , 97787.56 ) |
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4)
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( 97329.709 , 98241.121 ) |
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5)
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( 96808.023 , 98762.807 ) |
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Question 3 (1 point)
Suppose you want to determine the average height of college
basketball players in NCAA Division I. In a random sample of 15
players, the sample average is 71.271 inches with a standard
deviation of 5.2883 inches. What is the 95% confidence interval for
the average height of all NCAA D-I players?
Question 3 options:
Question 4 (1 point)
In a climate survey, it was determined that in a random sample
of 22 days, the average temperature in Kalamazoo at 2:00 PM in the
months of July and August is 78.1 degrees with a standard deviation
of 3.563 degrees. Using this information, a 99% confidence interval
for the average is (75.95, 80.25). Which of the following is the
appropriate interpretation of this interval?
Question 4 options:
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1)
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We are 99% confident that the average daily temperature for the
months of July and August at 2:00 PM for the days recorded is
between 75.95 and 80.25. |
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2)
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We are certain that 99% of the days in the months of August and
July will have a temperature at 2:00 PM between 75.95 and
80.25. |
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3)
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We are 99% confident that the proportion of all days'
temperatures will fall between 75.95 and 80.25. |
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4)
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We are 99% confident that the average daily temperature for the
months of July and August at 2:00 PM is between 75.95 and
80.25. |
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5)
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We cannot determine the proper interpretation of this
interval. |
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Question 5 (1 point)
You read an article in Golf Digest that someone with your
average drive distance will have an average score of 70.38. You
keep track of your scores for the next 14 rounds and see that your
average score is 76.29 with a standard deviation of 1.13 strokes.
You create a 95% confidence interval for your average score and it
is (75.64, 76.94). Given this information, what is the best
conclusion?
Question 5 options:
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1)
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We are 95% confident that your average score is greater than
70.38. |
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2)
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We are 95% confident that your average score is less than
70.38. |
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3)
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The average score does not significantly differ from
70.38. |
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4)
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We cannot determine the proper interpretation based on the
information given. |
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5)
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The percentage of rounds in which you score more than 70.38 is
95%. |
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Question 6 (1 point)
As an avid golfer, you want to estimate your average score for
18 holes of golf. Suppose you know that the standard deviation of
your score is 22.61 strokes and you want to find a sample mean that
is within 7.856 strokes of your true average for all rounds of golf
with 99% confidence. How many rounds would you need to play to
determine this?
Question 6 options:
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2)
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We do not have enough information to answer this question since
we were not given the sample mean. |
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Question 7 (1 point)
The owner of a local golf course wants to estimate the
difference between the average ages of males and females that play
on the golf course. He randomly samples 30 men and 22 women that
play on his course. He finds the average age of the men to be
38.866 with a standard deviation of 6.841. The average age of the
women was 43.341 with a standard deviation of 8.898. If a 90%
confidence interval is calculated to estimate the difference
between the two average ages, what is the margin of error? Assume
both population standard deviations are equal.
Question 7 options:
Question 8 (1 point)
It is believed that using a solid state drive (SSD) in a
computer results in faster boot times when compared to a computer
with a traditional hard disk (HDD). You sample 10 computers with an
HDD and note a sample average of 30.001 seconds with a standard
deviation of 6.7637 seconds. A sample of 12 computers with an SSD
show an average of 9.316 seconds with a standard deviation of
1.7934 seconds. Construct a 95% confidence interval for the
difference between the true average boot times of the two types of
hard drives. Assume the difference will represent (HDD-SSD) and
that the population standard deviations are statistically the
same.
Question 8 options:
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5)
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We only have the sample means, we need to know the population
means in order to calculate a confidence interval. |
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Question 9 (1 point)
A pharmaceutical company is testing a new drug to increase
memorization ability. It takes a sample of individuals and splits
them randomly into two groups. One group is administered the drug,
and the other is given a placebo. After the drug regimen is
completed, all members of the study are given a test for
memorization ability with higher scores representing a better
ability to memorize. You are presented a 90% confidence interval
for the difference in population mean scores (with drug - without
drug) of (-24.07, -9.68). What can you conclude from this
interval?
Question 9 options:
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1)
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We are 90% confident that the difference between the two sample
means falls within the interval. |
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2)
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There is no significant difference between the average
memorization abilities for those on the drug compared to those not
on the drug. |
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3)
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We are 90% confident that the average memorization ability of
those not on the drug is higher than those who are on the
drug. |
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4)
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We do not have enough information to make a conclusion. |
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5)
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We are 90% confident that the average memorization ability of
those on the drug is higher than those who are not on the
drug. |
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Question 10 (1 point)
You are in the market for a new car. You want to check whether
there is a significant difference between the fuel economy of
mid-size domestic cars and mid-size import cars. You sample 20
domestic car makes and find an average fuel economy of 34.451 MPG
with a standard deviation of 4.727 MPG. For imports, you sample 12
cars and find an average MPG of 30.351 MPG with a standard
deviation of 8.811. You use this information to calculate a 99%
confidence interval for the difference in mean fuel economy of
(-2.456, 10.656). Of the following statements, what is the best
interpretation of this interval?
Question 10 options:
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1)
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We do not know the population means so we do not have enough
information to make an interpretation. |
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2)
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We are 99% sure that the average difference in fuel economy of
all domestic cars and all import cars is between -2.456 and
10.656. |
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3)
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We are 99% confident that the difference between the average
fuel economy of all domestic mid-size cars and all import mid-size
cars surveyed is between -2.456 and 10.656. |
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4)
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We are certain that the difference between the average fuel
economy of all domestic mid-size cars and all import mid-size cars
is between -2.456 and 10.656. |
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5)
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We are 99% confident that the difference between the average
fuel economy of all domestic mid-size cars and all import mid-size
cars is between -2.456 and 10.656. |
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