math quiz

· The quiz covers Week 1 and Week 2 materials.

· Make sure your answers are as complete as possible and show your work/argument.  When there are calculations involved, you should show how you come up with your answers with critical work and/or necessary tables.  You must show why you choose certain answer for true-or-false or multiple choice questions. Answers that come straight from program software packages will not be accepted. 

· The quiz is open book and open notes . This means that you may refer to your textbook, notes, and online course materials, but you must work independently and may not consult anyone . The brief honor statement is on top of the exam. If you fail to put your name under the statement, your quiz will not be accepted. You may take as much time as you wish, provided you turn in your quiz via LEO by 11:59 pm ET on Sunday, June 7.

1. (10 points) True or False. Justify your answers for full credit.

(a) If the variance from a data set is zero, then all observations must be zero in this data set.

(b) The variance of a data set cannot be negative, but the standard deviation can be negative.

(c) Suppose the minimum for a data set is 0.12. A careless assistant records it as 1.2, which is the only mistake in the record keeping. The mistake will increase the mean as well as the median of the data set.

(d) The following distribution has a positive skew.

(e) Interquartile range can measure central tendency.

(For Questions 2 to 8) Choose the correct answer. Justify your answers for full credit. (2 points each)

2. An agency conducts a survey on the choice of vegetable by Americans.  It is reported by the agency that 57% of the respondents prefers broccoli. The value 57% is

a. a parameter,

b. a statistic,

c. neither of the above.

3. The volume of water in a glass is 12 oz. The value of 12 is from

a. a continuous data set,

b. a discrete data set,

c. neither of the above.

4. Which of the following is a qualitative variable?

a. Weight in kilograms

b. Number of days without precipitation

c. Ethnicity

d. Average daily temperature

5. For the following stem and leaf plot, how many numbers are there between 3 and 4? Please note the numbers in the stem are in ones.

 4|33  3|56  2|00456  1|00134  0|1245589 -0|0679 -1|005559 -2|7  

a. 0

b. 2

c. 11

d. 56

6. Identify the scale of measurement for the following military hierarchy: Lieutenant, Captain, Major

a. Interval

b. Nominal

c. Ratio

d. Ordinal

7. In a histogram, frequencies are represented by_______

a. Lines

b. Bars

c. portions of the pie

d. leaves

8. For the following histogram of test scores, The majority of scores came between______  

(a) 39.5 and 49.5

(b) 89.5 and 99.5

(c) 79.5 and 89.5

(d) 159.5 and 169.5

(For Questions 9 & 10)  The checkout times (in minutes) for 10 randomly selected customers at a large supermarket during the store’s busiest time are as follows:

9.  (5 points)  (Show work) Find the minimum, maximum, median, mode and mean of the checkout time. (Round the answers to one decimal place)

10.  (5 points)  (Show work) Prepare a frequency distribution with a class width of 2 minutes by completing the following table.

 __________________________________________________________________

(For Questions 11 & 12)  To qualify for a mortgage, an applicant needs to have a good FICO credit score. We chose a random sample of 5 applicants from a local bank, and their FICO scores are 760, 650, 820, 540 and 620. 

11.  (4 points)  (Show work) What is the standard deviation of the FICO scores in the sample?   Please show your intermediate calculation in the following table; you may not need all columns based on the formula you use. (Round the answer to two decimal places)

12.  (2 points)  (Show work) A data value is considered unusual if it’s above or below 2 standard deviations from the mean. Are any of these FICO scores considered unusual? Explain.

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