In a bag there are 30 identical balls numbered from 1 to 30. Choose one after the other three balls (without Off Reset). What is the average value of the sum of the numbers of three balls chosen? I am not sure on how i am gonna solve this so i think that we will have a variable X where X1 will be the number of first ball and X2 for the second and X3 for the third ball., so X=X1+X2+X3 and we want the average ,E(X)=E(X1)+E(X2)+E(X3) but i dont know how to estimate this. any ideas?