Question 1

The amount of time required for an oil and filter change on an automobile is normally
distributed with a mean of 45 minutes and a standard deviation of 10 minutes. A random sample
of 16 cars is selected. 90% of the sample means will be greater than what value?

Accepted Answer

The answer of The amount of time required for an...

Question 2

SCENARIO 7-6
Online customer service is a key element to successful online retailing. According to a marketing
survey, 37.5% of online customers take advantage of the online customer service. Random samples
of 200 customers are selected.
-Referring to Scenario 7-6, 95% of the samples proportions symmetrically around the population
proportion will have between _____% and _____% of the customers who take advantage of
online customer service.

Accepted Answer

The answer of SCENARIO 7-6
Online customer service is a key...

Question 3

As the sample size increases, the effect of an extreme value on the sample mean
becomes smaller.

Accepted Answer

A) True 
 B)False

Question 4

SCENARIO 7-2
The mean selling price of new homes in a small town over a year was $115,000. The population
standard deviation was $25,000. A random sample of 100 new home sales from this city was taken.
-Referring to Scenario 7-2, without doing the calculations, state in which of the following ranges the sample mean selling price is most likely to lie?

Accepted Answer

A)  $113,000 -- $115,000 
B)  $114,000 -- $116,000 
C)  $115,000 -- $117,000 
D)  $116,000 -- $118,000

Question 5

Why is the Central Limit Theorem so important to the study of sampling distributions?

Accepted Answer

A)  It allows us to disregard the size of the sample selected when the population is not normal. 
B)  It allows us to disregard the shape of the sampling distribution when the size of the population is large. 
C)  It allows us to disregard the size of the population we are sampling from. 
D)  It allows us to disregard the shape of the population when n is large.

Question 6

SCENARIO 7-7
A recent survey revealed that American's Christmas spending averaged $830. Use this as the
population mean American's Christmas spending. Suppose American's Christmas spending is
normally distributed with a standard deviation of $220. Random sample of size 100 are selected from
the population of American consumers.
-Referring to Scenario 7-7, the probability is 0.20 that the sample mean spending is at least how
much?

Accepted Answer

The answer of SCENARIO 7-7
A recent survey revealed that American's...

Question 7

The Central Limit Theorem ensures that the sampling distribution of the sample
mean approaches a normal distribution as the sample size increases.

Accepted Answer

A) True 
 B)False

Question 8

The Central Limit Theorem is considered powerful in statistics because it works
for any population distribution provided the sample size is sufficiently large and the population
mean and standard deviation are known.

Accepted Answer

A) True 
 B)False

Question 9

As the size of the sample is increased, the standard deviation of the sampling
distribution of the sample mean for a normally distributed population will stay the same.

Accepted Answer

A) True 
 B)False

Question 10

The amount of time required for an oil and filter change on an automobile is normally
distributed with a mean of 45 minutes and a standard deviation of 10 minutes. A random sample
of 16 cars is selected. What is the standard error of the mean?

Accepted Answer

The answer of The amount of time required for an...

Question 11

The amount of bleach a machine pours into bottles has a mean of 36 oz. with a
standard deviation of 0.15 oz. Suppose we take a random sample of 36 bottles filled by this
machine. The sampling distribution of the sample mean will be approximately normal only if the
population sampled is normal.

Accepted Answer

A) True 
 B)False

Question 12

The owner of a fish market has an assistant who has determined that the weights of catfish are normally distributed, with mean of 3.2 pounds and standard deviation of 0.8 pound. If a sample of
64 fish yields a mean of 3.4 pounds, what is probability of obtaining a sample mean this large or
Larger?

Accepted Answer

A)  0.0001 
B)  0.0013 
C)  0.0228 
D)  0.4987

Question 13

Major league baseball salaries averaged $3.26 million with a standard deviation of $1.2 million in a certain year in the past. Suppose a sample of 100 major league players was taken. What was the
Standard error for the sample mean salary?

Accepted Answer

A)  $0.012 million 
B)  $0.12 million 
C)  $12 million 
D)  $1,200.0 million

Question 14

If the population distribution is symmetric, the sampling distribution of the mean
can be approximated by the normal distribution if the samples contain 15 observations.

Accepted Answer

A) True 
 B)False

Question 15

Suppose μ = 50 and σ = 10 for a population. In a sample where n = 100 is
randomly taken, 90% of all possible sample means will fall between 49 and 51.

Accepted Answer

A) True 
 B)False

Question 16

μ The am = 110 gramount of tea leaves in a can froms and σ = 25 grams. A sam a particular production line is normple of 25 cans is to be selected. What is the probabilityally distributed with
that the sample mean will be between 100 and 120 grams?

Accepted Answer

The answer of μ The am = 110 gramount of...

Question 17

SCENARIO 7-5
According to an article, 19% of the entire population in a developing country have high-speed access
to the Internet. Random samples of size 200 are selected from the country's population.
-Referring to Scenario 7-5, the standard error of all the sample proportions is ______.

Accepted Answer

The answer of SCENARIO 7-5
According to an article, 19% of...

Question 18

μThe am = 110 gramount of tea leaves in a can froms and σ = 25 grams. A sam a particular production line is normple of 25 cans is to be selected. So, 95% of all samally distributed with ple
means will be greater than how many grams?

Accepted Answer

The answer of μThe am = 110 gramount of tea...

Question 19

SCENARIO 7-4
According to a survey, only 15% of customers who visited the web site of a major retail store made a
purchase. Random samples of size 50 are selected.
-Referring to Scenario 7-4, what proportion of the samples will have less than 15% of customers
who will make a purchase after visiting the web site?

Accepted Answer

The answer of SCENARIO 7-4
According to a survey, only 15%...

Question 20

SCENARIO 7-8
A consulting firm that surveyed consumers' holiday shopping behavior found that the percentage of
consumers from the U.S., Canada, and China who said that they planned to spend more on holiday
shopping were 40%, 34% and 73%, respectively. Treat these results as representations of the
populations. Random samples of size 150 are selected from each of the three countries.
-Referring to Scenario 7-8, 90% of the samples from Canada will have more than what
percentage of consumers who will spend more on holiday shopping?

Accepted Answer

The answer of SCENARIO 7-8
A consulting firm that surveyed consumers'...

Exam 7: Sampling Distributions

The amount of time required for an oil and filter change on an automobile is normally distributed with a mean of 45 minutes and a standard deviation of 10 minutes. A random sample of 16 cars is selected. 90% of the sample means will be greater than what value?

As the sample size increases, the effect of an extreme value on the sample mean becomes smaller.

Why is the Central Limit Theorem so important to the study of sampling distributions?

The Central Limit Theorem ensures that the sampling distribution of the sample mean approaches a normal distribution as the sample size increases.

The Central Limit Theorem is considered powerful in statistics because it works for any population distribution provided the sample size is sufficiently large and the population mean and standard deviation are known.

As the size of the sample is increased, the standard deviation of the sampling distribution of the sample mean for a normally distributed population will stay the same.

The amount of time required for an oil and filter change on an automobile is normally distributed with a mean of 45 minutes and a standard deviation of 10 minutes. A random sample of 16 cars is selected. What is the standard error of the mean?

The amount of bleach a machine pours into bottles has a mean of 36 oz. with a standard deviation of 0.15 oz. Suppose we take a random sample of 36 bottles filled by this machine. The sampling distribution of the sample mean will be approximately normal only if the population sampled is normal.

The owner of a fish market has an assistant who has determined that the weights of catfish are normally distributed, with mean of 3.2 pounds and standard deviation of 0.8 pound. If a sample of 64 fish yields a mean of 3.4 pounds, what is probability of obtaining a sample mean this large or Larger?

Major league baseball salaries averaged $3.26 million with a standard deviation of $1.2 million in a certain year in the past. Suppose a sample of 100 major league players was taken. What was the Standard error for the sample mean salary?

If the population distribution is symmetric, the sampling distribution of the mean can be approximated by the normal distribution if the samples contain 15 observations.

Suppose μ = 50 and σ = 10 for a population. In a sample where n = 100 is randomly taken, 90% of all possible sample means will fall between 49 and 51.

μ The am = 110 gramount of tea leaves in a can froms and σ = 25 grams. A sam a particular production line is normple of 25 cans is to be selected. What is the probabilityally distributed with that the sample mean will be between 100 and 120 grams?

SCENARIO 7-5 According to an article, 19% of the entire population in a developing country have high-speed access to the Internet. Random samples of size 200 are selected from the country's population. -Referring to Scenario 7-5, the standard error of all the sample proportions is ______.

μThe am = 110 gramount of tea leaves in a can froms and σ = 25 grams. A sam a particular production line is normple of 25 cans is to be selected. So, 95% of all samally distributed with ple means will be greater than how many grams?