#ed_op#P#ed_cl#
鴨鴨 寫到:100个人回答五道试题,有81人答对第一题,91人答对第二题, #ed_op#BR#ed_cl#85人答对第三题,79人答对第四题,74人答对第五题, #ed_op#BR#ed_cl#答对三道题或三道题以上的人算及格, #ed_op#BR#ed_cl#那么,在这100人中,至少有( )人及格
#ed_op#/P#ed_cl##ed_op#P#ed_cl#(法一)試排#ed_op#/P#ed_cl##ed_op#P#ed_cl#
#ed_op#/P#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#(法二)#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#先算出可容許錯誤的題目#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#100-81=19#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#100-91=9#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#100-85=15#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#100-79=21#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#100-74=26#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#19+9+15+21+26=90#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#共90題#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#要不及格,必須錯3題或4題,至少要錯3題#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#90/3=30---不及格人數最多有30人#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#100-30=70------及格人數最少有70人#ed_op#/DIV#ed_cl#