1. Pyramid Lake is on the Paiute Indian Reservation in Nevada. The lake is famous for cutthroat trout. Suppose a friend tells you that the average length of trout caught in Pyramid Lake is = 19 inches. However, a survey reported that of a random sample of 51 fish caught, the mean length was x = 18.4 inches, with estimated standard deviation s = 3.5 inches. Do these data indicate that the average length of a trout caught in Pyramid Lake is less than = 19 inches? Use = 0.05.

a. What is the level of significance?

b. What is the value of the sample test statistic? (Round your answer to three decimal places.)

2. Unfortunately, arsenic occurs naturally in some ground water. A mean arsenic level of = 8.0 parts per billion (ppb) is considered safe for agricultural use. A well in Texas is used to water cotton crops. This well is tested on a regular basis for arsenic. A random sample of 36 tests gave a sample mean of x = 7.1 ppb arsenic, with s = 2.2 ppb. Does this information indicate that the mean level of arsenic in this well is less than 8 ppb? Use = 0.01.

a. What is the level of significance? b. What is the value of the sample test statistic? (Round your answer to three decimal places.)

3. Let x be a random variable that represents red blood cell count (RBC) in millions of cells per cubic millimeter of whole blood. Then x has a distribution that is approximately normal. For the population of healthy female adults, suppose the mean of the x distribution is about 4.66. Suppose that a female patient has taken six laboratory blood tests over the past several months and that the RBC count data sent to the patient's doctor are as follows.

4.9

4.2

4.5

4.1

4.4

4.3

(i) Use a calculator with sample mean and standard deviation keys to find x and s. (Round your answers to two decimal places.)

x	=
s	=

(ii) Do the given data indicate that the population mean RBC count for this patient is lower than 4.66? Use = 0.05.

(a) What is the level of significance? b) What is the value of the sample test statistic? (Round your answer to three decimal places.)

4. Let x be a random variable that represents hemoglobin count (HC) in grams per 100 milliliters of whole blood. Then x has a distribution that is approximately normal, with population mean of about 14 for healthy adult women. Suppose that a female patient has taken 10 laboratory blood tests during the past year. The HC data sent to the patient's doctor are as follows.

16

17

15

20

15

13

15

16

15

10

(a)Use a calculator with sample mean and standard deviation keys to find x and s. (Round your answers to two decimal places.)

x=

s=

(b)Does this information indicate that the population average HC for this patient is higher than 14? Use = 0.01.

(i)What is the level of significance?

C)What is the value of the sample test statistic? (Round your answer to three decimal places.)

5. Snow avalanches can be a real problem for travelers in the western United States and Canada. A very common type of avalanche is called the slab avalanche. These have been studied extensively by David McClung, a professor of civil engineering at the University of British Columbia. Suppose slab avalanches studied in a region of Canada had an average thickness of = 67 cm. The ski patrol at Vail, Colorado, is studying slab avalanches in its region. A random sample of avalanches in spring gave the following thicknesses (in cm).

59	51	76	38	65	54	49	62
68	55	64	67	63	74	65	79

(i) Use a calculator with sample mean and standard deviation keys to find x and s. (Round your answers to two decimal places.)

x	=	cm
s	=	cm

(ii) Assume the slab thickness has an approximately normal distribution. Use a 1% level of significance to test the claim that the mean slab thickness in the Vail region is different from that in the region of Canada.

(a) What is the level of significance? b) What is the value of the sample test statistic? (Round your answer to three decimal places.)

6. Homser Lake, Oregon, has an Atlantic salmon catch-and-release program that has been very successful. The average fisherman's catch has been = 8.7 Atlantic salmon per day. Suppose that a new quota system restricting the number of fishermen has been put into effect this season. A random sample of fishermen gave the following catches per day:

12	6	11	12	5	0	2
7	8	7	6	3	12	12

(i) Use a calculator with sample mean and standard deviation keys to find x and s. (Round your answers to two decimal places.)

x	=	catches
s	=	catches

(ii) Assuming the catch per day has an approximately normal distribution, use a 5% level of significance to test the claim that the population average catch per day is now different from 8.7.(a) What is the level of significance? b) What is the value of the sample test statistic? (Round your answer to three decimal places.)

7.