3. The following diagram is a stem and leaf plot of the Life Optimism scores of the employees at La Trobe University.

Life optimism Stem-and-Leaf Plot Frequency Stem & Leaf 1.00 Extremes (=<4) 3.00 0 . 889 11.00 1 . 00023344444 37.00 1 . 5555666666777777777888888999999999999 22.00 2 . 0001111222222333444444 10.00 2 . 6666677778 Stem width: 10 Each leaf: 1 case(s) (a) How many employees scored 17 on the Life Optimism scale? (1mark)

(b) How many scores below ten were recorded? (1mark) (c) Is the distribution of the scores bell-shaped, negatively skewed or positively skewed? (1mark)

4. Here are the annual numbers of deaths from car accidents from 1994 through 2000: 5 5 3 4 6 9 3 Compute the mean, variance and standard deviation by hand. Show your work clearly. (5 marks)

5. A research assistant entering data into SPSS software accidentally put an extra "0" in one particular score in the 'Satisfaction' variable, recording it as 400 instead of 40. Explain how this error will affect the following summary statistics for the variable:

(a) measures of centre: median and mean. (2 marks)

(b) measures of spread: range, IQR (interquartile range), and standard deviation. (2 marks)