Susan wants to find an estimate for the number of fish in a lake. On Monday she catches 77 fish and marks each with a non-harmful dye.
She then returns those fish to the lake.
On Tuesday Susan catches 400 fish and notes down how many had dye on them.
Using her sampling information, Susan estimates the total number of fish in the lake to be
550.
How many of the fish Susan caught on Tuesday must have been marked with the dye?