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三星高級會員
2011-3-19 13:08#1
1. Michael tosses a coin 4 times. Among the 4 tosses, how many combinations show 2 heads and 2 tails?
2. A dice is thrown twice. How many combinations are there for one of the numbers shown up being '5'? -
二星初級會員
2011-4-27 16:07#2
新手一試，有錯請更正...
1.Assumed the coin is fair.
2 head 2 tail=(4C2)=6
2.Assumed the die is fair.
At least one "5" is obtained=2(6C1)=12