STAT 211 Business Statistics I Term 0143

1 STAT 211 Business Statistics I – Term 0143 KING FAHD UNIVERSITY OF PETROLEUM & MINERALS DEPARTMENT OF MATHEMATICS & STATISTICS DHAHRAN, SAUDI ARABIA STAT 211: BUSINESS STATISTICS I Major one

Name: Student ID#: Serial #:

Directions: 1) You must show all work to obtain full credit for questions on this exam. 2) DO NOT round your answers at each step. Round answers only if necessary at your final step to 4 decimal places.

Question Full Marks No Marks Obtained Q1 5

Q5 2 5 Q6 2 Q7

Total 70 2 STAT 211 Business Statistics I – Term 0143 Question 1: (5 pts) Identify each of the following studies as either Descriptive Statistics (D) or Statistical Inference (I): Type of the study Study (D or I) a. Examine the weights of a sample of 25 manufacturer parts to see if the average weight of all the parts produced by the process is 3 pounds. b. Post the average final score for the statistics class. c. Estimate the percentage of the US population that will vote for candidate “A” in the next presidential election. d. Select a random sample of 50 babies born in 2000 and estimate the birth weight of all babies born during the same year. e. Examine the weights of a sample of 10 candy bars to see if their average weight is 6 ounces.

Question 2: (5 pts) A manufacturer of electronic chips claims that less than 4% of his products are defective. When 500 toys were drawn from a large production run, 7% were found to be defective. Question Answer

1. What is the population of interest?

2. What is the sample?

3. What is the parameter?

4. What is the statistic?

5. Does the value 4% refer to the parameter or the statistic? 3 STAT 211 Business Statistics I – Term 0143 Question 3: (7 pts) Assume the following survey; a b

VARIABLE / QUESTION Level Of Variable type Measurement CAT or NUM 1. What is your gender?  Female  Male

2. What is your age (as of last birthday)? ______

3. What is your current major area of study?

 Accounting  Economics/Finance  Management  Retailing/Marketing  Other

4. What was your undergraduate cumulative grade point average?

5. How many different full-time jobs have you held in the past 10 years? 6. What do you expect your annual salary (in $000) to be immediately after completion of your graduate studies if you are employed full time?

7. How satisfied are you with the MBA program advisory services on campus? Extremely Extremely Neutral unsatisfied satisfied 1 2 3 4 5 6 7

a. In column a, specify the level of measurement (N=Nominal/ O=Ordinal/ S=Scale)

b. In column b, specify the variable type (NUM=numerical, CAT= categorical)? 4 STAT 211 Business Statistics I – Term 0143 Question 4: (3+1=4 pts) Does it take more time to get yourself removed from an email list

than it used to? A study of 100 large online retailers revealed the following:

Need Three Or More Clicks To Be

Year Removed Yes No 2009 39 61 2008 7 93 a. Construct a side-by-side bar chart of year and whether you need to click three or more times

to be removed from an email list.

b. What do these results tell you about whether more online retailers were requiring three or

more clicks in 2009 than in 2008?

Question 5: (2 pts) A survey was conducted from 665 consumer magazines on the practices

of their websites. The results are summarized in a copyediting table and a fact-checking table:

Copyediting as Compared Percentage to Print Content As rigorous 41 Less rigorous 48 Not copyedited 11 For copyediting, a student constructed a pie chart, and a Pareto chart, Which graphical method do

you think is best for portraying these data? Explain. 5 STAT 211 Business Statistics I – Term 0143 Question 6: (3+2=5 pts) the cost per ounce ($) for a sample of 14 dark chocolate bars: 0.55 0.57 0.57 0.68 0.72 0.77 0.86 0.9 0.92 0.94 1.14 1.41 1.42 1.51

a. Construct a stem-and-leaf display

b. Around what value, if any, is the cost of dark chocolate bars concentrated? Explain.

Question 7: (2pts) In 2000, a growing number of warranty claims on Firestone tires sold on

Ford SUVs prompted Firestone and Ford to issue a major recall. An analysis of warranty

claims data helped identify which models to recall. A breakdown of 2,504 warranty claims

based on tire size is given in the following table:

Number of Warranty For Tire Size Claims these data, the number of warranty claims by tire 23575R15 2,030 size, do you prefer using a Pareto chart or the pie chart 311050R15 137 or the 30950R15 80 bar chart? Why? 23570R16 83 331250R15 54 25570R16 58 Others 62 6 STAT 211 Business Statistics I – Term 0143 Question 8: (5+2+6+1+3+3+5=25 pts) The file contains the total cost ($) for four tickets, two juice, four soft drinks, four hot dogs, two game programs, two baseball caps, and parking for one vehicle at each of the 30 Major League Baseball parks during the 2009 season. These costs were

114 135 141 145 146 151 158 161 162 164 165 166 170 170 172 180 185 187 205 210 215 216 220 222 223 224 259 305 326 411 ∑x = 5908 , ∑x2 = 1275926

Frequency Distribution frequency Relative frequency 110<=x<160 7

1. Compute the Mean, Standard deviation, Mode, Median. Comment on the shape using these numbers.

2. Is the last observation suspect outlier? Explain. 7 STAT 211 Business Statistics I – Term 0143

3. Complete the frequency distribution and a percentage distribution for these costs.

4. Around which class grouping, if any, are the costs of attending a baseball game concentrated? Explain.

5. Using the midpoints of the class frequency distribution above, approximate the mean. Comment on the approximate value.

6. Construct the frequency histogram and comment on the graph.

7. Draw the Box-plot and comment on it. 8 STAT 211 Business Statistics I – Term 0143 Question 9: (2+2+4= 8 pts) Suppose A and B are two independent events for which P(A)= 0.20 and P(B) = 0.60. a. Find P(A/B).

b. Find P(A and B).

c. Find P(A or B).

Question 10: (4+3= 7 pts) A standard admissions test was given at three locations. 50% of the students took the test at location A, 30% at location B, and 20% at location C. The percentages of students from locations A, B, and C, who passed the test were 70%, 68%, and 77%, respectively. One student is selected at random from among those who took the test. a. What is the probability that the selected student passed the test?

b. If the selected student passed the test, what is the probability that the student took the test at location B? 9 STAT 211 Business Statistics I – Term 0143