In-class exercise 4: measure of central tendency and dispersion
Your name:
1. A cinema manager recorded the number of tickets sold per day over a 30-day promotional period. The number of tickets sold per day are as follows:
82, 76, 88, 89, 72, 64, 68, 58, 60, 71,
69, 58, 49, 55, 63, 50, 56, 59, 44, 52,
45, 53, 49, 52, 37, 44, 34, 22, 23, 15.
1) Find the (arithmetic) mean.
2) Find the median.
3) Find the mode(s).
4) Find the range.
5) Find the mean deviation.
6) Find the variance.
7) Find the standard deviation.
2. Load "light_bulb.Rdata".
1) Find the (arithmetic) mean of life_time.
2) Find the median of life_time.
3) Find the mode(s) of life_time.
4) Find the range of life_time.
5) Find the mean deviation of life_time.
6) Find the variance of life_time.
7) Find the standard deviation of life_time.
3. A dataset has a mean of 50 and a standard deviation of 5.
16. （1）Using Chebyshev’s Theorem, at least ____ of values must lie between 35 and 65, at least _______ of values must lie between 25 and 75, and at least _____ of values must lie between 0 and 100.
（2）Now suppose we know the data is roughly
normally distributed.
Using the Empirical Rule, approximately 68% of values must lie between _____ and ______, approximately 95% of values must lie between _____ and ______, and all (99.7 percent) of values must lie between _____ and ______.
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