 Solution

ID: past-exam-of-the-mathematics-course-of-the-year-1-of-the-natural-sciences-course-of-the-university-of-cambridge/2025/paper-2/12/e/i/solution

Only a green ball carries label four. After it is removed, nine of the remaining nineteen balls are green. The conditional probability is

\frac{9}{19} .

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