Explain how a data value is considered unusual if it’s above or below 2 standard deviations from the mean. Are any of these FOCI scores considered unusual?

  • 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) Quarterfinal 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

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  • 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

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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:

6 5 8 12 8

13 10 14 7 11

9.  (5 points)  (Show work) Find the minimum, maximum, median, mode and mean of the

checkout time. (Round the answers to one decimal place)

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

completing the following table.

Checkout Time Frequency Relative Frequency

5.0 – 6.9

7.0  – 8.9

9.0 – 10.9

11.0 – 12.9

13.0 – 14.9

__________________________________________________________________

(For Questions 11 & 12)  To qualify for a mortgage, an applicant needs to have a good FOCI

credit score. We chose a random sample of 5 applicants from a local bank, and their FOCI scores

are 760, 650, 820, 540 and 620.

11.  (4 points)  (Show work) What is the standard deviation of the FOCI 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)

FOCI

Score  x x

2

x-mean (x-mean)

2

760

650

820

540

620

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Sum

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 FOCI scores considered unusual?  Explain.

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