11.3

A psychiatrist is interested in finding a 98% confidence interval for the tics per hour exhibited by children with Tourette syndrome. The data below show the tics in an observed hour for 13 randomly selected children with Tourette syndrome. Round answers to 3 decimal places where possible.

2 10 2 0 6 7 7 11 8 1 11 0 9

a. To compute the confidence interval use a ?

t? or

z? distribution.

b. With 98% confidence the population mean number of tics per hour that children with Tourette syndrome exhibit is between ______and______.

c. If many groups of 13 randomly selected children with Tourette syndrome are observed, then a different confidence interval would be produced from each group. About _______percent of these confidence intervals will contain the true population mean number of tics per hour and about _______percent will not contain the true population mean a number of tics per hour.

11.4

In a survey, 23 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $30 and standard deviation of $4. Find the margin of error at a 90% confidence level.

Give your answer to two decimal places._________

11.5

If n=23n=23, xx=42, and s=11s=11, construct a confidence interval at a 95% confidence level. Give your answers to one decimal place.

_________< <_______

11.6

Karen wants to advertise how many chocolate chips are in each Big Chip cookie at her bakery. She randomly selects a sample of 61 cookies and finds that the number of chocolate chips per cookie in the sample has a mean of 11.1 and a standard deviation of 2.2. What is the 95% confidence interval for the number of chocolate chips per cookie for Big Chip cookies? Enter your answers accurate to one decimal place (because the sample statistics are reported accurate to one decimal place).

________ < < _______

11.7

You work for the U.S. Food and Drug Administration. You have gotten word that a drug manufacturing is not accurately reporting the contents of their liquid cold medication. Under Federal Regulations, "Variations from stated quantity of contents shall not be unreasonably large" (see section q of the regulation byclicking here).

The company that produces the cold medication is claiming that each bottle contains 355 milliliters of cold medication, which is about 12 fluid ounces. In order to determine if they are accurate in their reporting, you decide to randomly select 20 different bottles of cold medication and measure the amount of cold medication in each bottle (in milliliters). The results of each sample are shown below.

Bottle Number1 2 3 4 5 6 7 8 9 10

Milliliters358 356 349 358 345 346 360 354 358 349

Bottle Number11 12 13 14 15 16 17 18 19 20

Milliliters344 345 347 356 355 355 351 352 345 344

a)Use the data shown above to construct a 93% confidence interval estimate for the mean amount of cold medication the company is putting in their bottles. Record the result below in the form of (#,#). Round your final answer to two decimal places. _________

b)Is the company putting the claimed 355 milliliters of cold medication in their bottles? Explain. _________

• Yes, because 355 is inside of the confidence interval.
• Yes, because 355 is not inside the confidence interval.
• No, because 355 is inside the confidence interval.
• No, because 355 is not inside the confidence interval.