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ASSIGNMENT 1, Data Analysis & Decision Making DDM 501 MBA. IMT

Due at 1200 (noon) 15 October 2017 (Sunday)

Note:

1. Group submission, each team member receives the same score.

2. 5 points each, 20 questions, 100 points in total.

3. Hand-written and stapled submission in hardcopy. You do not need to knock my door and slide your

paper directly under my office door (A-006).

4. Late or partial submission will be penalized.

1.

A study found the following parts per billion of nitrosamines in a sample of domestic beers. (a) Construct

a frequency distribution of four classes with equal class sizes. (b) Construct another frequency distribution

of four classes using unequal class intervals or an open-ended interval for the highest class. (c) Which

frequency distribution is preferable? Why?

2.

Students were given a take-home statistics assignment and were asked to write down how long it took

them (in minutes). Their answers are shown below. (a) Make a dot plot. (b) Use your judgment to

construct a frequency distribution using whatever classes (bins) you wish. (c) Make a histogram. (d)

Describe the distribution. (e) Did your bin choices agree with Sturges’ Rule? If not, why not?

Dot plot suggests right-skewness. Sturges’ Rule suggests 6 classes, but 7 bins of size 5 might be needed

to show enough detail, while four classes of size 10 might not show enough detail.

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Ten part-time servers at a high-end restaurant were asked how many hours they worked last week and

how much they earned. The results are shown below. (a) Make a scatter plot. (b) Describe it. (c) What is

your best guess of the average hourly pay?

4.

Below is a sorted stem-and-leaf diagram for the measured speeds (miles per hour) of 49 randomly

chosen vehicles on highway I-80 in Nebraska. How many vehicles were traveling exactly the speed limit

(70 mph)?

A. 0

B. 1

C. 19

D. Impossible to tell

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Here are advertised prices of 21 used Chevy Blazers. Describe the distribution (center, variability, shape).

Range is from 7,000 to almost 18,000; median is around 11,500; interquartile range is about 11,000 to

14,000, with right-skewness.

6.

Briefly describe these data. Sketch its box plot and describe the sample succinctly.

7.

Here are descriptive statistics from Excel for annual per-pupil expenditures in 94 Ohio cities and home

sizes in a certain neighborhood. Very briefly compare the variability and shape of the two data sets.

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8.

Bob’s sample of freshman GPAs showed a mean of 2.72 with a standard deviation of 0.31. (a) What

range would you predict for all the grades? For the middle 95 percent? Explain. (b) Why might your

estimates be inaccurate? (Hint: Empirical Rule)

9.

The owner of a chicken farm kept track of each hen’s eating and egg production for many months, with

the results below. Which has more variation, feed consumption or egg output?

10.

Below are the ages of 21 CEOs. Find the mean, median, and mode. Are there any outliers? Explain.

46, 48, 49, 49, 50, 52, 54, 55, 57, 57, 58, 59, 60, 61, 62, 62, 63, 63, 65, 67, 75

11.

A national survey showed that most commuter cars contain only the driver. Hungry for a story, a campus

newspaper reporter asked five randomly chosen commuter students how many occupants, including the

driver, rode to school in their cars. Their responses were 1, 1, 1, 1, and 6. The next day a story appeared

in the paper headlined “University Commuters Double National Average Ridership.” Is this a reasonable

assessment of central tendency? How would you characterize the variability of the sample?

12.

Recently, a few companies have been accused of issuing stock options to their top executives at the

lowest stock price of the year. Executives can later sell these stock shares at a higher price and make a

large profit. In some companies, this happened several years in a row. An executive argued, “It’s just a

coincidence. There are about 250 trading days in a year, so there is a reasonable chance that my option

price just happened to be lowest of the year.” Discuss.

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Axolotl, Inc. decided to double the number of independent network file servers, each server being capable

of running its entire internal corporate network. Bob suggested that “doubling the number of file servers in

our corporate network will just double the chances of failure.” Is Bob right? Has the company made an

error?

14.

From the following tree, find the probability that a randomly chosen person will not get a vaccination and

will not get the flu.

A. .18

B. .60

C. .19

D. .70

15.

The manager of Ardmore Pharmacy knows that 25 percent of the customers entering the store buy

prescription drugs, 65 percent buy over-the-counter drugs, and 18 percent buy both types of drugs. What

is the probability that a randomly selected customer will buy at least one of these two types of drugs?

A. .90

B. .85

C. .72

D. .65

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Given the contingency table shown here, find P(V | S).

A. .2639

B. .1900

C. .0475

D. .4144

17.

The number of unique orders in which five items (A, B, C, D, E) can be arranged is:

A. 5.

B. 840.

C. 120.

D. 24.

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Given the contingency table shown here, find P(V or S).

A. .3825

B. .4300

C. .0475

D. .4775

19.

The following table shows the survival experience of 1,000 males who retire at age 65:

Based on these data, the probability that a 75-year-old male will survive to age 80 is:

A. 0.596

B. 1 – 0.596 = 0.404

C. 1 – 0.775 = 0.225

D. 0.769

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Which is a time series variable?

A. VISA balances of 30 students on December 31 of this year

B. Net earnings reported by Xena Corp. for the last 10 quarters

C. Dollar exchange rates yesterday against 10 other world currencies

D. Titles of the top 10 movies in total revenue last week