Question 1

A company wants to estimate,at a 95% confidence level,the proportion of all families who own its product.The most conservative estimate of the sample size that would limit the margin of error to be within 0.046 of the population proportion is:

Accepted Answer

The answer of A company wants to estimate,at a 95%...

Question 2

Each employee of a large company is encouraged to contribute,through payroll deduction,to an international charity.Annual contributions per employee follow (approximately)a normal distribution.You take a random sample of 25 employees and find that the sample mean annual contribution per employee is $501 with a standard deviation of $17.00.What are the boundaries for a 99% confidence interval for the population mean,rounded to two decimal places?

Accepted Answer

The answer of Each employee of a large company is...

Question 3

True or False.The statement: "The 90% confidence interval for the mean is (29.83 ,50.1)." can be interpreted to mean that the probability that the mean lies in the range (29.83 ,50.1)is 90%.

Accepted Answer

A confidence interval indicates that if we were to take many samples and build a confidence interval from each, 90% of those intervals would contain the true mean. It does not mean there is a 90% probability that the true mean lies within a specific interval.

Question 4

The Eks Survey Company employs 2000 people to conduct telephone surveys.Because many people don't like to answer such surveys,many "hang-ups" (whereby the person hangs up without completing the survey)occur.The owner of Eks wants to determine the mean number of "hang-ups" per employee on a particular day,using 95% confidence.He samples 50 employees,and finds that the mean number of "hang-ups" on that day was 41.0.Suppose that the standard deviation of the number of "hang-ups" for all employees is 21.8 What is the value of the margin of error? (round to four decimal places)

Accepted Answer

The answer of The Eks Survey Company employs 2000 people...

Question 5

Which of the following is not part of the procedure for estimating the value of a population parameter?
A)Selecting a sample
B)Collecting the required information from the members of the sample
C)Calculating the value of the sample statistic
D)Calculating the exact value of the corresponding population parameter

Accepted Answer

Calculating the exact value of the population parameter is not part of the estimation procedure, as estimation involves using sample data to infer the population parameter, not calculating it exactly.

Question 6

The Labor Bureau wants to estimate,at a 90% confidence level,the proportion of all households that receive welfare.The most conservative estimate of the sample size that would limit the margin of error to be within 0.030 of the population proportion is:

Accepted Answer

The answer of The Labor Bureau wants to estimate,at a...

Question 7

In a random sample of 53 items produced by a machine,the quality control staff found 5 of them to be defective.Calculate the point estimate of the population proportion of defective items.Round to 4 decimal places.

Accepted Answer

The answer of In a random sample of 53 items...

Question 8

Which of the following is not an acceptable condition for using the t distribution to make a confidence interval for  ?
A)The population from which the sample is drawn is right-skewed
B)The population from which the sample is drawn is normal
C)The population standard deviation is unknown
D)The population distribution has a mean of zero

Accepted Answer

The answer of Which of the following is not an...

Question 9

The correct formula for the limits of a confidence interval is:
A) 
B) 
C) 
D)

Accepted Answer

The answer of The correct formula for the limits of...

Question 10

A random sample of 354 persons showed that 306 do not have health insurance.Calculate the point estimate of the population proportion of persons who do not have health insurance.Round to 4 decimal places.

Accepted Answer

The answer of A random sample of 354 persons showed...

Question 11

A scientist is estimating the mean lifetime of a newly-discovered insect.From a sample of 88 insects,she finds a sample mean of 49.2 days.Suppose that the population standard deviation of all lifetimes is 2.500 days.What are the boundaries for a 90% confidence interval for the mean lifetime of the insect,rounded to two decimal places?

Accepted Answer

The answer of A scientist is estimating the mean lifetime...

Question 12

Determine the sample size n that is required for estimating the population mean.The population standard deviation  and the desired margin of error are specified.  94% margin of error 3 
A)8,836
B)8,836
C)8,835
D)8,837

Accepted Answer

The answer of Determine the sample size n that is...

Question 13

The Labor Bureau wants to estimate,at a 90% confidence level,the proportion of all households that receive welfare.A preliminary sample showed that 18.5% of households in this sample receive welfare.The sample size that would limit the margin of error to be within 0.036 of the population proportion is:

Accepted Answer

The answer of The Labor Bureau wants to estimate,at a...

Question 14

An advisor to the mayor of a large city wants to estimate,within 2.450 minutes,the mean travel time to work for all employees who work within the city limits.He knows that the standard deviation of all travel times is 11.35 minutes.He also wants to achieve a 95% confidence interval.He will poll a random sample of city employees.How many employees should he poll?

Accepted Answer

The answer of An advisor to the mayor of a...

Question 15

You are estimating the mean waiting time in line at a particular fast-food restaurant.You ask 30 customers,at varying times of the day,how long they waited in line before placing their order.You then take the average of these values and use this average to estimate the mean waiting time for all customers.The average of the 30 values is an example of a(n):
A)Chebyshev estimate
B)point estimate
C)interval estimate
D)confidence estimate

Accepted Answer

A point estimate is a single value given as an estimate of a population parameter, such as the mean waiting time in this case.

Question 16

An employee of the College Board analyzed the mathematics section of the SAT for 97 students and finds  = 30.2 and s = 13.0.She reports that a 97% confidence interval for the mean number of correct answers is (27.336,33.064).Does the interval (27.336,33.064)cover the true mean?
Which of the following alternatives is the best answer for the above question? 
A)Yes,(27.336,33.064)covers the true mean.
B)No,(27.336,33.064)does not cover the true mean.
C)We will never know whether (27.336,33.064)covers the true mean.
D)The true mean will never be in (27.336,33.064).

Accepted Answer

The answer of An employee of the College Board analyzed...

Question 17

A t distribution has a standard deviation of  .If the standard deviation is equal to 1.1055,what is the value of the t critical value for a 90% confidence interval?

Accepted Answer

The answer of A t distribution has a standard deviation...

Question 18

We are using the mean of a sample as a point estimate for the mean of a normal distribution with a standard deviation of 5.The margin of error,with 95% confidence,for this estimate is 0.860.What is the sample size?

Accepted Answer

The answer of We are using the mean of a...

Question 19

In a 1997 poll of 261 male,married,upper-level managers conducted by Joy Schneer and Frieda Reitman for Fortune magazine,31% of the men stated that their wives worked either full-time or part-time (Fortune,March 17,1997).What are the boundaries for a 99% confidence interval for p,the proportion of all male,married,upper-level managers whose wives work?

Accepted Answer

The answer of In a 1997 poll of 261 male,married,upper-level...

Question 20

Out of a sample of 639 gasoline purchases at a self-service gas station,544 were made with a credit or debit card.Obtain the predeterminated margin of error.Round your answer to three decimal places.

Accepted Answer

The answer of Out of a sample of 639 gasoline...

Quiz 8: Estimation of the Mean and Proportion

A company wants to estimate,at a 95% confidence level,the proportion of all families who own its product.The most conservative estimate of the sample size that would limit the margin of error to be within 0.046 of the population proportion is:

True or False.The statement: "The 90% confidence interval for the mean is (29.83 ,50.1)." can be interpreted to mean that the probability that the mean lies in the range (29.83 ,50.1)is 90%.

Which of the following is not part of the procedure for estimating the value of a population parameter?

The Labor Bureau wants to estimate,at a 90% confidence level,the proportion of all households that receive welfare.The most conservative estimate of the sample size that would limit the margin of error to be within 0.030 of the population proportion is:

In a random sample of 53 items produced by a machine,the quality control staff found 5 of them to be defective.Calculate the point estimate of the population proportion of defective items.Round to 4 decimal places.

Which of the following is not an acceptable condition for using the t distribution to make a confidence interval for ?

The correct formula for the limits of a confidence interval is:

A random sample of 354 persons showed that 306 do not have health insurance.Calculate the point estimate of the population proportion of persons who do not have health insurance.Round to 4 decimal places.

Determine the sample size n that is required for estimating the population mean.The population standard deviation and the desired margin of error are specified. 94% margin of error 3 A)8,836 B)8,836 C)8,835 D)8,837

A t distribution has a standard deviation of .If the standard deviation is equal to 1.1055,what is the value of the t critical value for a 90% confidence interval?

We are using the mean of a sample as a point estimate for the mean of a normal distribution with a standard deviation of 5.The margin of error,with 95% confidence,for this estimate is 0.860.What is the sample size?

Out of a sample of 639 gasoline purchases at a self-service gas station,544 were made with a credit or debit card.Obtain the predeterminated margin of error.Round your answer to three decimal places.