On the first day of trout season a team of biologists went with local trout anglers to the Macawber River  Each angler who caught at least 2 trout chose exactly 2 of these trout for the biologists to weigh  A total of 90 fish were weighed  The measurements show that at the beginning of this season the average trout in the Macawber River weighed approximately 1
6 kilograms
makes a generalization from a sample that is unlikely to be representative