How many ways are there to select 8 coins from a piggy bank with 100 pennies and 80 nickels ?
Ans. C(2+8-1,8)
Suppose the Question had been :-
How many ways are there to select 8 coins from a piggy bank with 6 pennies and 6 nickels?
Now what would have been the answer?
C(2+8-1,8) will be wrong here because initally there were lot of coins in both classes so i could choose atleast one of then from both But in this case what should be the answer ?
Should i calculate manually ?
2 penny , 6 nickel
3 penny , 5 nickel
and so on... But for a large number it would be a problem so how to do it ?