bush那题的又一变体

arthur

Totally 10 people, including Harry. Pick 1 out of 10 for president, then pick 1 out of 9 for secretary, pick 1 out of 8 for treasurer. What is the probability that Harry will be picked for either secretary or treasurer?
请问答案是否为1/5

lisaislisa

agree ^^
9/10*1/9+9/10*8/9*1/8