You need to calculate the probability of the outcomes X=2, 3, ..., 12 by

counting how many of the 36 possible outcomes (when the dice are

distinguishable) give each score and then dividing by 36:

P(X=2)=1/36

P(X=3)=2/36

P(X=4)=3/26

P(X=5)=4/36

:

:

P(X=12)=1/36

Once you have these probabilities your notes will tell you how to compute the

expectation and varianve etc.

RonL