A sample of 50 parrots are captured, tagged and released. Some time later, a second sample of 75 parrots are captured, of which 10 are found to have tags. Use these values to estimate the parrot population in the area.
I really don't know but here is a guess.
75 parrots = 10 tags
times both by 5
375 parrots = 50 tags
It is likely to be wrong though.
They caught 1/5 of the tagged parrots and that amounts to 75 parrots
5 * 75 = 375 parrots