FINAL EXAMINATION



NAME:.........................................................................

ID #:............................................................................






THE EXAM WAS ...........EASY ..........FAIR ..........DIFFICULT


FOR INSTRUCTORS USE

1.
(2)a.(2)b. (2)c.(2)d. (2)e.(5)f. (15)
2.
(5)a.(5)b. (10)
3.
(3)a.(3)b. (4)c. (10)
4.
(5)a.(5)b. (10)
5.
(5)a.(5)b. (10)
6.
(5)a.(5)b. (10)
7.
(10)
8.
(7)a.(8)b. (15)
9.
(10)
TOTAL
(100)


1. The following table provides information on life expectancies for a sample of countries. It also lists the number of people per television set in each country.

Country
Life exp.
Per TV
Country
Life exp.
Per TV
Angola
44
200
Mexico
72
6.6
Australia
76
2
Morocco
64
21
Cambodia
49
177
Pakistan
56
73
Canada
76
1.7
Russia
69
3.2
China
70
8
South Africa
64
11
Egypt
60
15
Sri Lanka
71
28
France
78
2.6
Uganda
51
191
Haiti
53
234
United Kingdom
76
3
Iraq
67
18
United States
75
1.3
Japan
79
1.8
Vietnam
65
29
Madagasgar
52
92
Yemen
50
38


a. Make a stemplot of the data for life expectancy and interpret

b. Compute the mean life expectancy for the countries listed in the table

c. Give the five-number summary of the data for the number of people per television set.

d. Construct a boxplot for the number of people per television set and interpret

e. Use the 1.5xIOR criterion to spot suspected outliers for the number of people per television set

f. the relationship between the number of people per television set (x) and life expectancy (y) has been studied. The least squares regression line is y=70.5-0.5x

Interpret 70.5 and -0.5

What would be the sign of the correlation coefficient r. please justify your answer.






2. Five hundred women and men were asked whether or not they would marry their current spouses if they were given a chance to do it over again. The probabilities associated with the results of the survey are given in the following table:


Would Marry the Current Spouse
Yes(Y)
No(N)
Female(F)
0.11
0.29
Male(M)
0.25
0.35


a. If one person is selected at random from these 500 persons, find the probability that

I. the response will be "yes", given that the person was female,

II. the respondent will be female given that the response is "yes",

III."the response will be yes" or "the respondent will be female".

b. Are the events "male" and "yes" independent? Explain why or why not.




3. An island has three species of bird. Species 1 accounts for 45% of the birds, of which 10% have been tagged. Species 2 accounts for 38% of the birds, of which 15% have been tagged. Species 3 accounts for 17% of the birds, of which 50% have been tagged.

a. Draw a tree diagram that summarizes this information

b. What is the probability that a randomly selected bird will be tagged?

c. If a tagged bird is observed, what is the probability that it is of species 2?



4. The treatment time of patients with an eye disease is normally distributed with mean 70 minutes and standard deviation 9 minutes.

a. Find the probability that a randomly selected patient's treatment will take between 58 and 82 minutes.

b. Suppose that 36 treatment times are randomly selected. What is the probability that average treatment time for these 36 treatments will exceed 73 minutes?


5. 15% of the United States population have no health insurance.

a. Find the probability that out of 15 randomly selected U.S. residents more than 7 of them will have a health insurance.

b. Use the normal approximation to find the probability that in a group 400 randomly selected people fewer than 17.5% will have no health insurance.


6. A zoologist is interested in determining the average life span of a certain species of elephant bred in captivity. The zoologist collects data on 15 elephants of this type from 15 different randomly selected zoos throughout America. The average life spans of these elephants is found to be 29.9 years with a standard deviation of 7.4 years.

a. Construct a 90% confidence interval for the true average life span of an elephant from this species.

b. Test the hypothesis that the average life span of an elephant from this species is more than 25 years. Use a=0.05.


7. A random survey of 500 pregnant women in New York City conducted by Epstein and Rogers indicated that 145 of them preferred a female obstetrician to a male obstetrician. Find a 95% confidence interval for the true proportion of all pregnant women living in New York City who prefer a female obstetrician.



PLEASE ANSWER EITHER ONE OF THE FOLLOWING TWO QUESTIONS

8. An insurance company wants to know if the average speed at which men drive cars is higher than that of women drivers. The company took a random sample of 27 cars driven by men on a highway and found the mean speed to be 68 miles per hour with a standard deviation of 2.2 miles. Another sample of 18 cars driven by women on the same highway gave a mean speed of 65 miles per hour with a standard deviation of 2.5 miles. Assume that the speeds at which all men and all women drive cars on this highway are both normally distributed.

a. Construct a 99% confidence interval for the difference between the mean speeds of cars driven by all men and all women drivers on this highway.

b. Test at the a=0.01 significance level if the mean speed of cars driven by all men drivers on this highway is higher than that of cars driven by all women drivers.

8. A lottery commissioner's office in a state wanted to find if the proportions of all women and men who play the lottery often are different. A sample of 500 men taken by the commissioner's office showed that 165 of them play the lottery often. Another sample of 300 women showed that 69 of them play the lottery often.

a. Is there evidence that the proportions of all women and all men who play the lottery often are different? (State the null and alternative hypotheses and give the P-value.)

b. Construct a 95% confidence interval for the difference between the proportions of all women and all men who play the lottery often.


9. Prior to the time that the germ theory of disease was established (around 1870), the mortality rate from surgery was very high because of infection. Louis Pasteur and Joseph Lister were largely responsible for the germ theory. Lister believed that if carbolic acid were used as a disinfectant, the patients chance of survival might be improved. He used it to scrub everything in the operating room. He even sprayed the air with carbolic acid. Lister compared 40 operations (amputations) in which this procedure was used with 35 amputations in which it was not used. The results are summarized in the following table:

Patient Lived
Patient Died
Carbolic Acid Used
34
6
Carbolic Acid Not Used
19
16


At the a=0.01 level of significance, test whether the outcome of the surgery (patient lived or died) is independent of the use of carbolic acid.