A researcher is trying to estimate the number of fish in Lak

A researcher is trying to estimate the number of fish in Lake Sparky. She captures 90 fish in the lake and tags them. Later, after the tagged fish have had time to intermingle with the rest of the fish population, she captures another group of fish and notes that of the 105 she captured, 15 of them had tags. Use this information to estimate the fish population in Lake Sparky.

Solution

in 15 tagged fish,total fish population = 105
in 90 tagged fish, fish population = 105*90/15 = 630

So,
total fish population = 630