Answer:
15 Blue Jays
Step-by-step explanation:
Number of Blue Jays tagged = 22
Number of Blue jays captured = 550
Estimate of the Blue Jay population = 825
We need to find out how many Blue Jays out of 550 were tagged ones. Remember that in the beginning there were no tagged Blue Jays and Marley tagged 22 of them. This means total number of tagged Blue Jays in the entire population is 22. Rest of the blue Jays are not tagged. Marley calculated the estimated Blue Jay population using the proportions.
Assume that from 550, x Blue Jays were tagged. Out of 825 Blue Jays, 22 are tagged. The proportion of tagged Blue Jays in 550 must be equal to the proportion of tagged Blue Jays in entire population. i.e.

Since, the number of Blue Jays cannot be in decimal, we round it up to the nearest integer 15.This means, out of 550 trapped 15 Blue Jays were the tagged ones. Based on this Marley estimated the Blue Jays Population size.