The time it takes an average athlete to swim 100 meters freestyle at age x years can be modeled as t(x) = 0.18m2 8.463x + 147.376 seconds (a) Numerically estimate to the nearest tenth the rate of change of the time for a 15year-old swimmer to swim 100 meters freestyle. seconds per year (of age) (b) Determine the percentage rate of change of swim time for a 15year-old. (Round your answer to one decimal place.) % per year (of age) (c) Is a 15year-old swimmer's time improving or getting worse as the swimmer gets older? The rate of change shows that swim time is Select v . The swimmer's time is Select v