Re: probabilty mass function

Quote:

Originally Posted by

**legakwa** For assessment

You roll two fair standard dice and record the num-

bers showing. Let T be the random variable \the sum of the two

numbers rolled" and D be the random variable \the absolute value of

the dierence between the two numbers rolled".

(a) Find the probability mass function of T.

(b) Find the expectation of T.

(c) Find the probability mass function of D.

(d) Find the expectation D

@legakwa, you must show work on this problem.

Look at this webpage. The coefficients tell us the number of ways a sum can happen. For example $\displaystyle 4x^9$ tells us that the sum of nine occurs four ways out of thrifty-six pairs.

Now you work out the probability mass function of T.

For the second part: D can have values $\displaystyle 0,1,\cdots,5$