A student has a box containing 25 computer disks, of which
Chapter 0, Problem 6.101(choose chapter or problem)
A student has a box containing 25 computer disks, of which 15 are blank and 10 are not. She randomly selects disks one by one and examines each one, terminating the process only when she finds a blank disk. What is the probability that she must examine at least two disks? (Hint: What must be true of the first disk?)
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