To see whether the claims for a new long-life battery were justified, a consumers' group tested a random sample of 20 batteries. Each battery was subjected to a standard heavy load until burnout, providing the following 20 lifetimes ( in minutes): 65.1 58.4 64.9 76.0 67.8 75.1 76.7 64.2 74.9 77.6 58.0 68.0 73.3 75.4 76.0 59.4 65.4 74.7 76.6 81.3 using a cell width of 5 minutes,
a. Graph the relative frequency distribution.
b. Approximately what are the mean and mode? Mark the mean as the balancing point ?