A. Answering this problem requires you to know how to solve for each of those parameters. The variance is dependent on the mean, and the mean is dependent on your attendance, so thats not going to remain the same. The standard deviation is just the square of the variance, so again - wont remain the same. The range is the difference between the lowest and the highest value - as the incorrect entry is neither the highest or the lowest, the range will not change.

B. Do you know how to determine the mean from a frequency distribution?

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Where x is the midpoint of your classes (150-159 would be 154.5), and f is the frequency of each class - so (154.5)(5).

C. Do you know how percentile works? I can tell you the data is symetric. They tell you that that 5th Percentile is 135 minutes, and the 50th Percentile (aka, the mean) is 175, and the 95th Percentile is 215 minutes. If we were constructing a graph, with a scale from 0 to 100, 5 and 95 would be an equal distance from the left and right edges yes? So for that graph to be symetric, an equal number of "stuff" would have to be between 5 and 50, as there is between 95 and 50. Is there?