It is generally assumed that $75 \%$ of type-l diabetics comply with their insulin regimen. Suppose that a 12 -year-old type-l diabetic boy comes to clinic and shows a 5 -lb. weight gain over 1 year (actually, because of measurement error, assume this is an actual weight gain from 4.5 to 5.5 lbs.). The boy claims to be taking his insulin medication.
What is the probability that he is telling the truth?