3.1

13 mean= 30.5, median= 31.3, mode= No mode

14 mean= 93.1, median= 87.9, mode= No mode

15 mean= 3670, median= 3830, mode= 4090

16 mean= 266, median= 266, mode= 260

17

  1. The graph is skewed right, so the mean is greater than the median.

  2. The graph’s standard deviation is pretty symmetrical, so the mean is approximately equal to the median.

  3. The graph is skewed left, so the median is greater than the mean.

3.2

5 sample variance= 36, standard deviation= 6

6 sample variance= 100, standard deviation= 10

7 population variance= 16, standard deviation= 4

8 population variance= 57, standard deviation= 7.55

9 sample variance= 196, standard deviation= 14

10 population variance= 25, standard deviation= 5

14 range= 25, sample standard deviation= 8.43

24

  1. 6 seconds

  2. Since the histogram is pretty symmetrical, the empirical rule applies. Based on the empirical rule, about 68% of the eruption lengths are between 1 standard deviation away from the mean, 95% are between 2 standard deviations, and 99.7% are between 3 standard deviations away.

  3. The percentage of eruptions that last between 92 and 116 seconds is about 95%.

  4. The actual percentage is 95.45%.

  5. 16% of eruptions last less than 98 seconds.

  6. The actual percentage of eruptions that last less than 98 seconds is 11.36%.