To estimate populations, biologists make a first visit to a site, set traps, catch animals, and mark a number of animals before releasing them again. next, the biologists make a return visit, set traps again, and catch a number of animals. the biologists can get a reasonable estimate of the total animal population by comparing ratios from their data in the proportion: M2/M1 = N2/NE where
M2 is the number of animals that have been marked as caught during the return visit.
M1 is the number of animals originally caught and marked the first time.
N2 is the total number of animals caught on return visit.
NE is the estimate of the total animal population.
A biologist studying fox squirrels has the following data:
During his first visit, he caught and marked 20 squirrels. A week later, he returned and caught 18 squirrels, 6 of which had his mark. Set up the proportion, and solve to estimate the total population of fox squirrels in this area.