(19*0+12*1+1*2)/32=7/16, right?

19 cases, no pumps need repairing;
12 cases, 1 pump needs repairing;
1 case (all pumps are out of order), 2 pumps need repairing.

所有跟帖： 

• 回复：(19*0+12*1+1*2)/32=7/16, right? -jinjing- ♀ (39 bytes) () 06/18/2010 postreply 20:22:27

• don't say that! it is funny we reached the same point. -皆兄弟也- ♂ (0 bytes) () 06/18/2010 postreply 21:53:14