UCAT conditional probability questions
Given that means: keep only the cases that meet the condition, then find the share. If one person who passed is picked, divide by the number who passed, not everyone. Try two below.
Decision Making · Question 1 of 20:00 / 1:03
A course records outcomes. | Group | Passed | Did not pass | |---|---:|---:| | Morning | 31 | 11 | | Evening | 21 | 41 | One person who passed is selected at random. What is the probability that the person attended in the morning, to one decimal place?
Use counts, not formulas
Turn percentages into counts of a round total, like 1,000. Then the answer is a fraction of two counts.
| Step | Example: 40% from A, 15% of A fail; 60% from B, 5% of B fail |
|---|---|
| Fails from A | 1,000 × 0.4 × 0.15 = 60 |
| Fails from B | 1,000 × 0.6 × 0.05 = 30 |
| Picked failure is from A | 60 ÷ 90 = 66.7% |
Keep going
Two events together: UCAT independent and dependent events
Every Decision Making type: DM question types and methods