the answer is 4 cats.because in 100 minutes, the max no of mouse caught by each cat is 100/3=33, so at least 4 cats are needed since 4 times 33 equal to132 which is greater than 100 while 3 times33 equal to 99 which is smaller than 100
[ 本帖最後由 Jan-Ove-Waldner 於 2010-2-8 13:51 編輯 ]