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bigsmallwhat (bigsmallwhat) 于 (Tue Jan 30 16:46:23 2007) 提到:
#1
A bag contains a total N balls with either blue or red color. If five balls
are randomly chosen from the bag, the probability 1/2 that all five balls
are blue. What is the smallest value for N for which this is possible?
My trial: 5 blue + 1 red (right or wrong?)
#2
You are given 5 bags containing 100 coins each. The bags can contain coins
of 3 different types that look identical. The fi
