THIS IS AN OLD EXAM AND I WAS HOPING TO GET THE ANSWERS TO PRACTICE!! THANKS

MATH201

Fall 2009

Exam 1a

Name: ____________________________________________________________

Lab Section: (circle one)

20LF 12:20 1:1030LTu 2:00 2:5040LF10:10 11:00

21LF1:25 2:1531LF9:05 9:5541LTu11:00 11:50

22LM12:20 1:1032LTu 12:30 1:2042LM10:10 11:00

23LM1:25 2:1533LM 9:05 9:5543LTh4:30 5:20

60LM11:15 12:0570L M2:30 3:20

61LF11:15 12:0571L M3:35 4:25

62LTh 12:00 12:5072L F2:30 3:20

63LTh 3:30 4:2073L F3:35 4:25

Instructions:

1.Do not start until instructed to do so.

2.Turn off cell phones and other devices and place them under your seat.You may NOT use them as a calculator.

3.You may use a scientific calculator.No cell phone or graphing calculators are permitted.

4.Code your 5- or 9-digit UD Student ID Number in the Student ID Number space on your scansheet and fill in the bubbles.Also complete the Last Nameand First Name sections.You dont need to complete any other sections on the scansheet.

5.Choose the best answer to each question.Each question is worth 4 points.

1.Serious cervical injuries to professional football players in the last several years have heightened interest in reducing spinal injuries.The following summary tables display the % of spinal injuries categorized by cause and the% categorized by particular sport.Which graphical method would do the best job of presenting these data?

Spinal Injury Causes%Sports Spinal Injury Causes%

Falls20.8Diving66.0

Motor Vehicles47.7Football 6.1

Sports14.2Gymnastics 2.2

Violence14.6Horseback riding 2.0

Other 2.7Non-skiing winter sports 2.3

Snow skiing 3.8

Surfing 3.1

Trampoline 2.6

Wrestling 2.3

Other 9.6

a.Descriptive statistics by sport

b.Bar chart or pie chart

c.Box plot

d.Histogram

e.Stem-and-leaf plot

Questions 2, 3:Recently published paperback books have been priced according to the following probability distribution (X = price of book).

2.On average, what is the expected price of the paperback books?

XP(X)

$ 5.50.15

$ 7.50.35

$ 8.00.40

$10.00.10

a.7.75b.7.575c.50d.7.65e.none of these.

1. What is the probability a paperback book will cost $7.50 or more?

a..35b..50c..15d.1.00 e..85

4.A small printing company estimates that the number of jobs submitted per day has a distribution that is approximately mound-shaped with a mean of 83 and a standard deviation of 10.On what percentage of days is the number of jobs submitted less than 53?

a..3%b.99.85%c.99.7%d..15%e.At most 11%

5.If the mean =4 and the standard deviation = 3, what is the Z score for an observation = 8?

a.12b.4c.4d.1.33e.1.33

6.ABC News claims that the number of homes reached by their late night (11:30 p.m.) newscast, Nightline, has a mean of 3.4 million homes with a standard deviation of 0.6 million homes.If the ABC claim is true, what percentage of the nights does this newscast reach fewer than 2.2 million homes? There is no assumption about the shape of the distribution.

a.At most 25%b.95% c.2.5% d.At most 12.5%e.At least 75%

Questions 7 9:A poison hot-line receives, on average, four calls per hour on its toll-free number.

7.What are the mean and standard deviation, respectively, for the number of calls received per hour?

a.4 and 4 b.4 and 2c.2 and 2d.2 and 4e.None of these.

8.For any given hour, what is the probability that it will receive at least 3 calls but less than 7 calls per hour?

a..516b..456c..711d..651e..889

9.What is the probability the hot-line will receive 3 calls during any one hour?

a. 0.195b.0.433c.0.168d. 0.805e.0.238

Questions 10 - 12: A local company has received complaints that its telephone lines are always busy.After examining thousands of company calls, an investigation into the complaints reveals that 70% of the telephone calls to the company are of a personal nature.Before the company can crack down on the personal call problem, the employees union lodges a formal complaint with the company.The union claims that the 70% number is outrageous and gives a sample of 20 random calls as evidence of its views.

10.Assuming the 70% number is accurate, how many of the 20 calls do we expect to be of a personal nature?

a.6b.14c.10d.20e.None of these.

11.Find the probability that at least 15 of the calls were of a personal nature.

a..893b..416c..584d..762e..238

12.Suppose 7 calls out of the 20 were observed to be of a personal nature.What would you infer about the 70% number quoted by the company.

a.Since the probability of such a result is so small, we would doubt the companys claim.

b.Since only 35% of the sample of 20 calls are of a personal nature, we would doubt the companys claim.

c.Observing 7 personal calls in a sample of 20 is not unusual, so we would not doubt the companys claim.

d.Nothing can be said about the companys claim, based on the sample of 20.

13.A tax collector takes random samples of property values for 16 tax-exempt properties in two different cities.The boxplots summarize the data from each city.Which of the following statements is true?

a.The mean value of city A's data is higher than that of city B's data.

b.City A's data has more variation.

c.75% of the values in city B's data are below about $64 million.

d.City B's data is left skewed.

e.The upper (right)inner fence for city B is around $300 million.

14.In a study of the effects of television commercials on 7-year-old children, the attention span (in seconds) of children watching commercials for clothing, food, and toys is measured.

Descriptive Statistics: AttSpan

VariableCommercial NMeanStDevVarianceMedianRangeIQR

AttSpanClothes928.678.4371.0030.0024.0015.50

Food1242.429.8496.8143.0032.0017.25

Toys1153.094.7022.0952.0013.00 9.00

Which distribution of attention spans has the most variation?

a.Clothes

b.Food

c.Toys

d.Cannot tell

Questions 15, 16:A large paint retailer has had numerous complaints from customers about under fill paint cans.As a result, the retailer has begun inspecting incoming shipments of paint from suppliers.Shipments with under fill problems will be returned to the supplier.A recent shipment contained 2,440 gallon-size cans. The retailer sampled 50 cans and weighed each on a scale capable of measuring weight to 4 decimal places.Properly filled cans weigh 10 pounds.

15.What is the population?

1. The 50 cans of paint.
2. The shipment of 2,440 cans of paint.
3. The paint retailers customers.
4. The weight of the paint cans.
5. The average weight of the paint cans.

16.What is the variable?

a.The 50 cans of paint.

b.The shipment of 2,440 cans of paint.

1. The paint retailers customers.
2. The weight of the paint cans.
3. The average weight of the paint cans.

17.According to a recent poll, 51% ( 4%) of Americans say it would have been better for the government to have spent less money to stimulate the economy (Gallup, Inc., August 18, 2009).This is an example of

a.a quantitative variable.

b.a Poisson probability calculation.

c.descriptive statistics.

d.inferential statistics.

e.the Empirical Rule.

18.Which of the following is a valid probability distribution?

a.X4920 b.X2356

P(X)-.3.4.9P(X).15.15.45.35

c.X0123d.X-2-10

P(X).1.3.3.2P(X).25.50.25

e.a and d are valid

Questions 19 21:Two random samples of colleges gave the following amounts that the college spends on sports per student.For one sample, only male sports were considered and for the other sample only female sports were considered.

VariableMeanStDevMinimumMedianMaximum

Males92243830623929122220

Females84972745993809916249

Stem-and-leaf of Males

Leaf Unit = 1000

001

023

055555

0666777777

08888889999999

100001111

12222233

145

16

1

2

22

Stem-and-leaf of Females

Leaf Unit = 100

09

1

2

39

4

524899

60455889999

700023468

834499

9123899

1001233

110235

1207

133

14 6

15

162

19.What percentage of colleges in the male sample spend at least $10,000 per student for male sports?

a.19%

b.31%

c.38%

d.62%

e.cannot be determined

20.Suppose we use this sample information to generalize to the population of colleges, and we assume that the distribution of expenses for male sports is mound shaped (symmetrical)We would expect about 95% of the colleges to spend between what amounts on male sports per student?

a.$623 and $22,220

b.$2,500 and $17,500

c.$5,394 and $13,054

d.$1,564 and $16,884

e.$0 and$20,714

21.Find the first quartile for the expenses for female sports.

a.$1,275

b.$10,275

c.$8,000

d.$6,800

Questions 22, 23:Shown below are descriptive statistics for two samples of river lengths (in miles), one from the United States and one from Europe.

VariableNMinimumQ1MedianQ3Maximum

UnitedStates36259.0363.8528.5782.32315.0

Europe32210.0460.8613.0918.32290.0

22.Use the boxplot rule to determine whether there are outliers (suspect or otherwise) in each sample.

a.no outliers in either sample

b.both samples contain outliers

c.outliers in the U.S. sample only

d.outliers in the Europe sample only

23.Suppose the maximum length in the Europe sample had been recorded incorrectly.Instead of 2290 miles, it should have been 2390 miles.What effect would this change have on the mean, median, and standard deviation?

a.Only the mean and median would increase.

b.The mean and standard deviation would decrease, but the median would remain unchanged.

c.The mean and standard deviation would increase, but the median would remain unchanged.

d.The mean would increase, but the standard deviation and median would not change.

e.All three summary measures would increase.

24.It is reported that 77% of workers aged 16 and over drive to work alone.Choose 8 workers at random.What is the probability that exactly 3 drive to work alone?

a.

b.

c.

d.

e.

25.Security analysts devote full-time efforts to evaluating the investment worth of a narrow list of stocks, e.g., bank stocks, computer stocks, or pharmaceutical stocks.The following variables are of interest to security analysts.Which one of the following is a discrete random variable?

1. The percentage change in yearly earnings between 1996 and 1997 for a particular firm.
2. The time until a pharmaceutical company gains approval from the U.S. Food and Drug Administration to market a new drug.
3. The number of new products introduced per year by a firm.
4. The type of firm: bank, computer, or pharmaceutical.
5. The price to earnings ratio of each company.

26.Indicate which form of the exam you have (see the cover page).

a.Exam 1a

b.Exam 1b

c.Exam 1c

d.Exam 1d