how to understand: must be invested among 4 possible opportuniti
even if we should change 16 to 20....we get C(21,4)=...
sorry, C(21,4)=... wrong; C(24,4)=... right,if we should change
皆兄弟也
2010-09-08 10:00:33how to understand: must be invested among 4 possible opportuniti