Question 1

A local health center noted that in a sample of 400 patients 80 were referred to them by the local hospital.
a.Provide a 95% confidence interval for all the patients who are referred to the health center by the hospital.
b.What size sample would be required to estimate the proportion of hospital referrals with a margin of error of 0.04 or less at 95% confidence?

Accepted Answer

The answer of A local health center noted that in...

Question 2

The Highway Safety Department wants to study the driving habits of individuals. A sample of 81 cars traveling on the highway revealed an average speed of 67 miles per hour with a standard deviation of 9 miles per hour.
a.Compute the standard error of the mean.
b.Determine a 99% confidence interval estimate for the speed of all cars.

Accepted Answer

The answer of The Highway Safety Department wants to study...

Question 3

In order to estimate the proportion of individuals who read at least one book per month, a random sample of individuals was selected and they were asked whether or not they read at least one book per month. Their responses are shown below.  Develop a 95% confidence interval for the proportion of people in the population who read at least one book per month.

Accepted Answer

The answer of In order to estimate the proportion of...

Question 4

The average score of a sample of 87 senior business majors at UTC who took the Graduate Management Admission Test was 510 with a standard deviation of 36. Provide a 98% confidence interval for the mean of the population.

Accepted Answer

The answer of The average score of a sample of...

Question 5

The manager of a grocery store wants to determine what proportion of people who enter his store are his regular customers. What size sample should he take so that at 97% confidence the margin of error will not be more than 0.1?

Accepted Answer

The answer of The manager of a grocery store wants...

Question 6

Information regarding the price of a roll of camera film (35 mm, 24 exposure) for a sample of 12 cities worldwide is shown below. Determine a 95% confidence interval for the population mean.

Accepted Answer

The answer of Information regarding the price of a roll...

Question 7

A simple random sample of 144 items resulted in a sample mean of 1257.85 and a standard deviation of 480. Develop a 95% confidence interval for the population mean.

Accepted Answer

The answer of A simple random sample of 144 items...

Question 8

A quality control technician is checking the weights of a product. She takes a random sample of 8 units and weighs each unit. The observed weights are shown below. Assume the population has a normal distribution.  Provide a 95% confidence interval for the mean weight of the units.

Accepted Answer

The answer of A quality control technician is checking the...

Question 9

A statistician employed by a consumer testing organization reports that at 95% confidence he has determined that the true average content of the Uncola soft drinks is between 11.7 to 12.3 ounces. He further reports that his sample revealed an average content of 12 ounces, but he forgot to report the size of the sample he had selected. Assuming the standard deviation of the population is 1.28, determine the size of the sample.

Accepted Answer

The answer of A statistician employed by a consumer testing...

Question 10

An Excel printout of the descriptive measures of daily checking account balances (in dollars) of customers of First Daisy Bank is shown below. Develop a 95% confidence interval estimate for the mean of the population of the checking balances.

Accepted Answer

The answer of An Excel printout of the descriptive measures...

Question 11

A local electronics firm wants to determine their average daily sales (in dollars.) A sample of the sales for 36 days revealed average sales of $139,000. Assume that the standard deviation of the population is known to be $12,000.
a.Provide a 95% confidence interval estimate for the average daily sales.
b.Provide a 97% confidence interval estimate for the average daily sales.

Accepted Answer

The answer of A local electronics firm wants to determine...

Question 12

A simple random sample of 36 items resulted in a sample mean of 40 and a standard deviation of 12. Construct a 95% confidence interval for the population mean.

Accepted Answer

The answer of A simple random sample of 36 items...

Question 13

Six hundred consumers were asked whether they would like to purchase a domestic or a foreign automobile. Their responses are given below.  Develop a 95% confidence interval for the proportion of all consumers who prefer to purchase domestic automobiles.

Accepted Answer

The answer of Six hundred consumers were asked whether they...

Question 14

In order to determine the average weight of carry-on luggage by passengers in airplanes, a sample of 25 pieces of carry-on luggage was collected and weighed. The average weight was 18 pounds. Assume that we know the standard deviation of the population to be 7.5 pounds.
a.Determine a 97% confidence interval estimate for the mean weight of the carry-on luggage.
b.Determine a 95% confidence interval estimate for the mean weight of the carry-on luggage.

Accepted Answer

The answer of In order to determine the average weight...

Question 15

In a poll of 600 voters in a campaign to eliminate non-returnable beverage containers, 210 of the voters were opposed. Develop a 92% confidence interval estimate for the proportion of all the voters who opposed the container control bill.

Accepted Answer

The answer of In a poll of 600 voters in...

Question 16

In order to determine the summer unemployment rate among college students, a pilot sample was taken; and it was determined that ten percent of the individuals in the sample were unemployed. Using the results of the pilot study and a 95% confidence, what size sample would be required to estimate the proportion of unemployed college students if we want the margin of error not to exceed 3 percent?

Accepted Answer

The answer of In order to determine the summer unemployment...

Question 17

In a random sample of 400 residents of Chattanooga, 320 residents indicated that they voted for the Democratic candidate in the last presidential election. Develop a 95% confidence interval estimate for the proportion of all Chattanooga residents who voted for the Democratic candidate.

Accepted Answer

The answer of In a random sample of 400 residents...

Quiz 8: Interval Estimation