Marmots are animals that live in burrows underground are a good target species for studies about population changes over time because they don't migrate. Professor Dorsey's research group traps 84 marmots and tags them. They return the tagged marmots to the wild and, a week later, trap 750 marmots. Of those marmots, 45 are marked. To the nearest whole number, what is the best estimate for the marmot population?