# module 6 and exam 6

Problem Set 6.1

1. A company manufactures a certain over-the-counter drug. The company samples 80 pills and finds that the mean amount of drug in the pills is 325.5 mg with a standard deviation of 10.3 mg. Find the 90% confidence interval for the mean of all the pills.

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2. A large number of chain saws have been sold. You contact 250 customers and find that it takes an average of 42 minutes to assemble the chain saws with a standard deviation of 17.3 minutes. Find the 98 % confidence limit for the mean time that it takes for all customers to assemble the chain saws.

3. A large number of bags of cement have been manufactured. You sample 10 of the bags and find that they have a mean weight of 91.5 pounds with a standard deviation of 8.8 pounds. Find the 90 % confidence limit for the mean of the weight of all of the cement bags.

4. A total of 200 rods have been manufactured. You sample 50 of the rods and find that they have a mean length of 15.5 inches with a standard deviation of 1.73 inches. Find the 80 % confidence limit for the mean length for all of the rods.

# Problem Set 2

Problem Set 6.2

1. A new drug for migraine headaches has been introduced to the market. You would like to know if migraine patients prefer the old drug or the new drug. So, you sample 190 patients that have used both drugs and you find that 52% of the sampled patients prefer the new drug, 48% of the patients prefer the old drug. Find the 90% confidence limit for the proportion of all patients that prefer the new drug. Can you be 90% confident that a majority of all the patients prefer the new drug?

2. Suppose that you are a nurse and you are assigned to do checkups of people one day per week in a certain village. You have a total of 300 patients in the village. You have the option of doing the checkups in the mornings or in the afternoons. Therefore, you ask 35 patients and find that 62% prefer afternoon appointments while 38% prefer morning appointments. Find the 95% confidence limit for the proportion of all patients that prefer afternoon appointments.

# Exam Preparation

Exam Preparation

Please note that as you prepare for the exam, you do not have to memorize the equations. An equation sheet just like the equation sheet below will be supplied with your exam. So, included with your exam will be:

1) Standard Normal Table

2) Student’s t-table

3) An Equation sheet (see below).

Therefore, as you do practice problems in preparation for the exam, use the three items listed above and onlythose three items!