This graph compares the growth rate of three bacterial species: Geobacillus stearothermophilus, Escherichia coli, and Neisseria meningitidis, all of which have different doubling times: 20, 30, and 40 minutes respectively. G. stearothermophilus will grow at a much faster rate than E. coli or N. meningitidis even though its doubling time is only 10 and 20 minutes shorter respectively.