- The problem involves calculating the probability that a randomly selected child from a group of 100 children (50 with measles and 50 without) will test positive for measles, given that the test is 95% accurate.
- Since the test is 95% accurate, it correctly identifies 95% of those with measles (true positives) and 95% of those without measles (true negatives).
- For the 50 children with measles: 95% of 50 = 47.5 test positive (true positives).
- For the 50 children without measles: 5% of 50 = 2.5 test positive (false positives), because 5% of healthy children are misdiagnosed.
- Total positive tests = true positives + false positives = 47.5 + 2.5 = 50.
- Probability that a randomly selected child tests positive = total positive tests / total children = 50 / 100 = 0.5 or 50%.
Parent Tip: Review the logic above to help your child master the concept of pocahontas worksheet.
