Exam 11: Confidence Intervals for Means

A manufacturer of cheese filled ravioli supplies a pizza restaurant chain.Based on data collected from its automatic filling process, the amount of cheese inserted into the ravioli is normally distributed.To make sure that the automatic filling process is on target, quality control inspectors take a sample of 25 ravioli and measure the weight of cheese filling.They find a sample mean weight of 15 grams with a standard deviation of 1.5 grams.What is the margin of error at 90% confidence?

n=10, =13.0, s = 4.5.Find a 95% confidence interval for the mean.

In a metal fabrication process, metal rods are produced to a specified target length of 15 feet.Suppose that the lengths are normally distributed.A quality control specialist collects a random sample of 16 rods and finds the sample mean length to be 14.8 feet and a standard deviation of 0.65 feet.The 95% confidence interval for the true mean length of rods produced by this process is ________________________ .

In a metal fabrication process, metal rods are produced to a specified target length of 15 feet.Suppose that the lengths are normally distributed.A quality control specialist collects a random sample of 16 rods and finds the sample mean length to be 14.8 feet and a standard deviation of 0.65 feet.Which of the following statements is true?

A sociologist develops a test to measure attitudes about public transportation, and 27 randomly selected subjects are given the test.Their mean score is 76.2 and their standard deviation is 21.4.Construct the 95% confidence interval for the mean score of all such subjects ________________________ . Please fix alignment

A manufacturer of cheese filled ravioli supplies a pizza restaurant chain.Based on data collected from its automatic filling process, the amount of cheese inserted into the ravioli is normally distributed.To make sure that the automatic filling process is on target, quality control inspectors take a sample of 25 ravioli.The correct value of t^* to construct a 98% confidence interval for the true mean amount of cheese filling is ________________________ .

Grandma Gertrude's Chocolates, a family owned business, has an opportunity to supply its product for distribution through a large coffee house chain.However, the coffee house chain has certain specifications regarding cacao content as it wishes to advertise the health benefits (antioxidants) of the chocolate products it sells.In order to determine the mean % cacao in its dark chocolate products, quality inspectors sample 36 pieces.They find a sample mean of 55% with a standard deviation of 4%.The correct value of t^* to construct a 90% confidence interval for the true mean % cacao is ________________________ .

A large software development firm recently relocated its facilities.Top management is interested in fostering good relations with their new local community and has encouraged their professional employees to engage in local service activities.They wish to determine the average number of hours the firm's professionals volunteer per month.They find the 95% confidence interval of 14.62 to 15.78.Which of the following is the correct interpretation?

A manufacturer of cheese filled ravioli supplies a pizza restaurant chain.Based on data collected from its automatic filling process, the amount of cheese inserted into the ravioli is normally distributed.To make sure that the automatic filling process is on target, quality control inspectors take a sample of 25 ravioli and measure the weight of cheese filling.They find the 99% confidence interval of 14.16 to 15.84 grams.Which of the following is the correct interpretation?

A manufacturer of cream filled donuts wants to make sure that its automatic filling process is on target.Based on a sample of 25 donuts the mean weight of cream filling is estimated to be 15 grams with a standard deviation of 1.5 grams.However, the quality control inspectors wish to estimate the mean weight of cream filling more accurately so that they can be 99% confident that it is within 0.25 grams of the true mean.How many donuts should they sample?

A small business ships specialty homemade candies to anywhere in the world.Past records indicate that the weight of orders is normally distributed.Suppose a random sample of 16 orders is selected and each is weighed.The sample mean was found to be 110 grams with a standard deviation of 14 grams.The standard error of the mean is ________________________ .

A credit union took a random sample of 40 accounts and yielded the following 90% confidence interval for the mean checking account balance at the institution: $2183 < $\mu$ (balance) < $3828.Which of the following is the correct interpretation?

A small business ships specialty homemade candies to anywhere in the world.Past records indicate that the weight of orders is normally distributed.Suppose a random sample of 16 orders is selected and each is weighed.The sample mean was found to be 110 grams with a standard deviation of 14 grams.Which of the following statements is true?

A small business ships specialty homemade candies to anywhere in the world.Past records indicate that the weight of orders is normally distributed.Suppose a random sample of 16 orders is selected and each is weighed.The sample mean was found to be 110 grams with a standard deviation of 14 grams.The 90% confidence interval for the true mean weight of orders is ________________________ .

Grandma Gertrude's Chocolates, a family owned business, has an opportunity to supply its product for distribution through a large coffee house chain.However, the coffee house chain has certain specifications regarding cacao content as it wishes to advertise the health benefits (antioxidants) of the chocolate products it sells.In order to determine the mean % cacao in its dark chocolate products, quality inspectors sample 36 pieces.They find a sample mean of 55% with a standard deviation of 4%. What is the margin of error at 95% confidence?

A pharmaceutical company wants to answer the question whether it takes longer than 45 seconds for a drug in pill form to dissolve in the gastric juices of the stomach.A sample was taken from patients taken the given drug in pill form and times for the pills to be dissolved were measured.b.State assumptions of the test.

Top management at a large software company wishes to estimate the average number of hours its firm's professional employees volunteer in the local community.Based on past similar studies, the standard deviation was found to be 2.22 hours.If top management wants to estimate the average number of hours volunteered per month by their professional staff to within one hour with 99% confidence, how many randomly selected professional employees would they need to sample?

Grandma Gertrude's Chocolates, a family owned business, has an opportunity to supply its product for distribution through a large coffee house chain.However, the coffee house chain has certain specifications regarding cacao content as it wishes to advertise the health benefits (antioxidants) of the chocolate products it sells.In order to determine the mean % cacao in its dark chocolate products, quality inspectors sample 36 pieces.They find a sample mean of 55% with a standard deviation of 4%. The 90% confidence interval for the true mean % cacao is ________________________ .

Analysis of a random sample of 250 Illinois nurses produced a 95% confidence interval for the mean annual salary of $42,846 < $\mu$ (Nurse Salary) < $49,686

In a metal fabrication process, metal rods are produced to a specified target length of 15 feet.Suppose that the lengths are normally distributed.A quality control specialist collects a random sample of 16 rods and finds the sample mean length to be 14.8 feet and a standard deviation of 0.65 feet.The standard error of the mean is ________________________ .