The following table shows the probability distribution for a discrete random variable.

C. 30.47

Step-by-step explanation:

The mean of discrete random variable i.e. the expected value of X is given by :-

Now by using the given table, the expected value of X is given by :-

Hence, the  mean of discrete random variable= 30.47

for finding the midpoint of any given 2 pair of points simply add the respective x coordinates with other x coordinate and the y coordinate with other y coordinate and divide them by 2

in your question it will be :

(3+1)/2 for the x coordinate of mid point i.e 2

[8+(-4)]/2 for the y coordinate of midpoint i.e 2

so coordinates of mid point of points (3,8) and (1,-4) will be (2,2)