In how many ways 30 identical balls can be DISTRIBUTED among 4 boys??
Ans) Let they get a,b,c,d respectively. You requireto find the non negative integral results of a+b+c+d=30 (as they add up to 30)the formula is ^{n+r+1}C_{r-1} where n=30 and r= 4(a,b,c,d)therfore 33C3 = 5456