Question 22
At 0:00 a box contains five black balls and one white ball. One black ball is added every 10 seconds at 0:10,0:20,0:30,…,1:00, and one white ball is added at 0:23. One ball is drawn at 0:00,0:30 and 1:00, after any black-ball addition at that time. Find the probability of drawing a white ball within the minute.
Editorial sampling assumption: each draw is uniform among balls currently in the box, and the selected ball is removed without replacement. The event is at least one white ball among the three draws.
Editorial sampling assumption: each draw is uniform among balls currently in the box, and the selected ball is removed without replacement. The event is at least one white ball among the three draws.