→ yyiitt1003:我的GWD答案給的是50,不過至少我知道解法了,謝謝 11/13 01:36
※ 引述《yyiitt1003 (懷念補習班的日子)》之銘言：
: 以下問題,實在想不出來思考盲點,請各位高手幫忙解惑了~
: Running at their respective constant rates, macgine X takes 2 days
: longer to produce w widgets than machine Y.At these rates,if the
: machines together produce 5/4w widgets in 3 days,how many days would
: it take machine X alone to produce 2w widgets?
: Ans.12
: A certain roller coaster has 3 cars,and a passenger is equally likely
: to ride in any 1 of the 3 cars each time that passenger rides the roller
: coaster. IF a certain passenger is to ride the roller coaster 3 times,
: what is the probability that the passenger will ride in each of the 3 cars?
: Ans. 2/9
: There are 8 books on a shelf,of which 2 are paperbacks
: and 6 are hardbacks.How many possible selections of 4 books from this
: shelf include at least one paperback?
: Ans. 50
: 做越多題,越來越沒信心了..
補充最後一題
用(全部的方法)-(全選精裝版)
= (C8取4) - (C6取4) = 55 你應該是看錯答案......
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