Readiness Assessment Test 4
Wednesday, February 2, 2000

Recall that you should answer each question three times. You will receive one point for each correct answer for a maximum of three points per question.

Below are summary statistics for the daily high temperatures in Berkeley, California, and Minneapolis, Minnesota, for 1996—refer to this summary for #1-3, #4-6, and #7-9.

                                      Berkeley         Minneapolis
Minimum                                 48                       13
Lower quartile                         60                        53
Median                                   64                        70
Upper quartile                         70                        85
Maximum                                98                      103

#1-3. The interquartile range for Minneapolis is

    A.    10
    B.     32
    C.     53
    D.     90

#4-6. The range in temperatures for Berkeley is

    A.    10
    B.    90
    C.    less than the range for Minneapolis
    D.    greater than the range for Minneapolis

#7-9.. Approximately what percentages of the days have highs of 70 degrees or above for the
two locations?

    A.    Both about 50%
    B.    Minneapolis is 70 or above about half the time, and Berkeley is 70 or above about 25% of the time
    C.    Minneapolis is 70 or above about half the time, and Berkeley is 70 or above about 75% of the time
    D.    There is not enough information to answer the question.

#!0-12 A boxplot is

  1. a numerical summary of numerical data.
  2. A numerical summary of categorical data.
  3. a visual display for categorical data.
  4. A visual display of the five-number summary for numerical data.

#13-15. Which of the following is NOT a measure of spread (or variability) of data: the

  1. interquartile range
  2. standard deviation
  3. range
  4. median

#16-18. The cumulative grade point average (GPA) of a random sample of 550 female students was obtained. It was found that the average GPA in this ample was 3.00 with a standard deviation of 0.30. GPA’s have a bell-shaped distribution (normal curve). The empirical rule states that about 95% of female students will have GPA’s be between

  1. 2.70 and 3.30
  2. 2.40 and 3.60
  3. 2.10 and 3.90
  4. 2.00 and 4.00

#19-21. A recent Gallup poll of probable primary voters in New Hampshire reported that 40% of Republican voters supported the nomination of Sen. John McCain of Arizona. The 95% margin of error for the poll was plus or minus 4%. Which of the following is the 95% confidence interval for the proportion of all potential primary voters supporting McCain?

  1. 36% to 44%
  2. 35% to 45%
  3. 32% to 48%
  4. 30% to 50%

#22-24. An instructor assigns each of her 500 students to identify a random sample of 36 students from Penn State. Using their different samples, each student calculates a 90% confidence interval for the mean (average) GPA of all Penn State students. The University Registrar’s Office reports that the mean GPA of all Penn State students is 2.90. About how many of the student’s 500 intervals will contain the true value 2.90?

  1. 0
  2. 90
  3. 450
  4. 500

#25-27. The following ranges are possible 95% confidence intervals for the percentage of Americans who think they have enough spending money. For which of the confidence intervals could you definitely conclude (statistically) that at least 50% of the population thinks they have enough spending money?

  1. 41% to 49%
  2. 49% to 54%
  3. 52% to 58%
  4. Answers B and C.

#28-30. A random sample of adult women was obtained and their view about abortion was determined. The sample percentage favoring abortion on demand was 52%. A 90% confidence interval for the proportion of all adult women favoring abortion on demand turned out to be 48% to 56%. Which one of the null hypotheses below should be rejected in a manner consistent with the confidence interval given?

    1. H0 : proportion = .50 vs. H1 : proportion ¹ .50
    2. H0 : proportion = .52 vs. H1 : proportion ¹ .52
    3. H0 : proportion = .55 vs. H1 : proportion ¹ .55
    4. H0 : proportion = .60 vs. H1 : proportion ¹ .60

True (A) or False (B).

#31-33. A confidence interval provides an estimate of a population parameter.        A B

#34-36. A 95% confidence interval for the mean amount students spend on textbooks each semester is $246 to $288. This tells us that 95% of all students spend between $246 and $288.        A B

#37-39. A 99% confidence interval for a proportion might not contain the true population proportion.
                                                                                                                              A B

#40-42. A 90% confidence interval would be wider than the corresponding 99% confidence interval.
                                                                                                                              A B

#43-45. A narrow confidence interval is more desirable than a wide confidence interval.
                                                                                                                              A B

 

#13-15. The number of CD’s owned by a sample of 8 students was as follows:

    40     50     50     65     65     70     100     2000

The number of CD’s owned by one of these students was 2000, which is an outlier (a value out of range with the rest of the values). .Therefore, the mean is more appropriate to use to describe the sample values than the median.