Secretariat won the Kentucky Derby with times for successive quarter-mile segments of $25.2 \mathrm{s}, 24.0 \mathrm{s}, 23.8 \mathrm{s},$ and $23.0 \mathrm{s} .$ (a) Find his average speed during each quarter-mile segment. (b) Assuming that Secretariat's instantaneous speed at the finish line was the same as the average speed during the final quarter mile, find his average acceleration for the entire race. (Horses in the Derby start from rest.)