@Ankur: Got it!!!!!...this confusion arise coz u right.....'No. Of ways we can distribute r similar balls in n numbered boxes,......what usually mention in books is that No. Of ways we can distribute N similar balls in r numbered boxes..n the formula which I was applying is same as u...n+r-1Cr-1=n+r-1Cn (remember: this formulas I mention based on 'No. of ways to distribute n similar balls in r boxes which is just oppose of your definition....don't get confused like me...) you done it by latter one...I done it by former one...the replacement btw n & r made whole confusion...nothing else...

M.A Economics

Delhi School of Economics

2013-15

Email Id:sumit.sharmagi@gmail.com