Exam 11: Confidence Intervals and Hypothesis Tests for Means

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?

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?

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 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. State the hypotheses to test this question.

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?

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 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.

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