How do I know how to figure out which of these situations are best modeled with exponential decay, and I know there is more than 1, The amount of medicine in a system decreases 40 milligrams per hour, and or The number of mold cells doubles every hour, and or 25 species become extinct or endangered each year, and or A scientist claims glaciers are losing 1 percent of their mass each year, and finally and or The deer population of a state decreases 0.25% each year. Please assist so I can make proper choices.