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In-class Assignment Four

  1. Suppose the scores on a recent exam in your statistics class were as follows: 78, 95, 60, 93, 55, 84, 76, 92, 62, 83, 80, 90, 64, 75, 79, 32, 75, 64, 98, 73, 88, 61, 82, 68, 79, 78, 80, 85.
    1. Create a stemplot for these test scores using each 10a value once on the stem.
    2. Create a stemplot for these test scores using each 10 values twice on the stem.
    3. Compare the stemplots created in parts (a) and (b). Are any features of the data apparent in one of them but not the other one? Explain.
  2. Refer to the previous test scores.
    1. Create a histogram for the test scores.
    2. Explain how you decided how many intervals to use for the historgram.
    3. Comment on the shape of the histogram.
  3. Refer to the previous test scores.
    1. Find the median for the test scores.
    2. Find the mean for the test scores and compare to the median. Which one is larger, and why?
    3. Find the standard deviation for the test score.
    4. Do you think the standard deviation would be smaller or larger if the test score of 32 were to be removed from the data?
  4. Refer to the previous test scores.
    1. Create a five number summary.
    2. Create a boxplot.
    3. The test score of 32 should have been identified as an outlier. Which of the three reasons would you use to explain this outlier? Should the outlier be removed when a description of the test scores presented?