3. The method of tree-ring dating gave the following years A.D. for an archaeological excavation site. Assume that the population ofxvalues has an approximately normal distribution.

1,215

1,222

1,222

1,180

1,268

1,316

1,275

1,317

1,275

(a)Use a calculator with mean and standard deviation keys to find the sample mean yearxand sample standard deviations. (Round your answers to four decimal places.)

x

= A.D.s= yr

(b)When finding an 90% confidence interval, what is the critical value for confidence level? (Give your answer to three decimal places.)

t_c=

What is the maximal margin of error when finding a 90% confidence interval for the mean of all tree-ring dates from this archaeological site? (Round your answer to the nearest whole number.)

E=

Find a 90% confidence interval for the mean of all tree-ring dates from this archaeological site. (Round your answers to the nearest whole number.)lower limit A.D.upper limit A.D.

4. The method of tree-ring dating gave the following years A.D. for an archaeological excavation site. Assume that the population ofxvalues has an approximately normal distribution.

1,194

1,313

1,222

1,299

1,268

1,316

1,275

1,317

1,275

(a)Use a calculator with mean and standard deviation keys to find the sample mean yearxand sample standard deviations. (Round your answers to four decimal places.)

x= A.D.

s= yr

(b)Find a 90% confidence interval for the mean of all tree-ring dates from this archaeological site. (Round your answers to the nearest whole number.)lower limit A.D.upper limit A.D.

5. How much does a sleeping bag cost? Let's say you want a sleeping bag that should keep you warm in temperatures from20Fto45F.A random sample of prices ($) for sleeping bags in this temperature range is given below. Assume that the population ofxvalues has an approximately normal distribution.

50	65	95	90	100	105	30	23	100	110
105	95	105	60	110	120	95	90	60	70

(a)Use a calculator with mean and sample standard deviation keys to find the sample mean pricexand sample standard deviations. (Round your answers to four decimal places.)x= $ s= $

(b)Using the given data as representative of the population of prices of all summer sleeping bags, find a 90% confidence interval for the mean priceof all summer sleeping bags. (Round your answers to two decimal places.)lower limit $

upper limit $

6. How much do wild mountain lions weigh? Adult wild mountain lions (18 months or older) captured and released for the first time in the San Andres Mountains gave the following weights (pounds):

65

101

126

120

60

64

Assume that the population ofxvalues has an approximately normal distribution.(a) Use a calculator with mean and sample standard deviation keys to find the sample mean weightxand sample standard deviations. (Round your answers to four decimal places.)

x=	lb
s=	lb

(b) Find a 75% confidence interval for the population average weightof all adult mountain lions in the specified region. (Round your answers to one decimal place.)

lower limit	lb
upper limit	lb

7. Do you want to own your own candy store? Wow! With some interest in running your own business and a decent credit rating, you can probably get a bank loan on startup costs for franchises such as Candy Express, The Fudge Company, Karmel Corn, and Rocky Mountain Chocolate Factory. Startup costs (in thousands of dollars) for a random sample of candy stores are given below. Assume that the population ofxvalues has an approximately normal distribution.

99

177

128

91

75

94

116

100

85

(a) Use a calculator with mean and sample standard deviation keys to find the sample mean startup costxand sample standard deviations. (Round your answers to four decimal places.)

x=	thousand dollars
s=	thousand dollars

(b) Find a 90% confidence interval for the population average startup costsfor candy store franchises. (Round your answers to one decimal place.)

lower limit	thousand dollars
upper limit	thousand dollars

8. Over the past several months, an adult patient has been treated for tetany (severe muscle spasms). This condition is associated with an average total calcium level below 6 mg/dl. Recently, the patient's total calcium tests gave the following readings (in mg/dl). Assume that the population ofxvalues has an approximately normal distribution.

9.90

9.40

10.90

9.30

9.40

9.80

10.00

9.90

11.20

12.10

(a)Use a calculator with mean and sample standard deviation keys to find the sample mean readingxand the sample standard deviations. (Round your answers to four decimal places.)

x= mg/dls= mg/dl

(b)Find a 99.9% confidence interval for the population mean of total calcium in this patient's blood. (Round your answer to two decimal places.)lower limit mg/dlupper limit mg/dl

(c)Based on your results in part (b), do you think this patient still has a calcium deficiency? Explain.Yes. This confidence interval suggests that the patient may still have a calcium deficiency.Yes. This confidence interval suggests that the patient no longer has a calcium deficiency. No. This confidence interval suggests that the patient may still have a calcium deficiency.No. This confidence interval suggests that the patient no longer has a calcium deficiency.

9. What percentage of hospitals provide at least some charity care? Based on a random sample of hospital reports from eastern states, the following information is obtained (units in percentage of hospitals providing at least some charity care):

57.5

56.5

53.3

66.1

59.0

64.7

70.1

64.7

53.5

78.2

Assume that the population ofxvalues has an approximately normal distribution.(a)Use a calculator with mean and sample standard deviation keys to find the sample mean percentagexand the sample standard deviations. (Round your answers to four decimal places.)x= % s= %

(b)Find a 90% confidence interval for the population averageof the percentage of hospitals providing at least some charity care. (Round your answers to one decimal place.)

lower limit %upper limit %