Two dentists A and B make a survey of the state of the teeth of 200 children in a village. Dr. A selects a simple random sample of 20 children and counts the number of decayed teeth for each child, with the following results. Number of decayed 0 1 2 3 4 5 6 7 8 9 10 teeth/child Number of children 8 4 2 2 1 1 0 0 0 1 1 Dr. B, using the same dental techniques, examines all 200 children, recording merely those who have no decayed teeth. He finds 60 children with no decayed teeth. Estimate the total number of decayed teeth in the village children a) Using A's results only b) Using both A's and B's results c) Are the estimates unbiased? d) Which estimate do you expect to be more precise?