This has something to do with expectations and its properties.
The sales per day for a product is estimated as follows based on past records
Daily demand (X) / Probaility
10 / .1
11 / .2
12 / .4
13 / .3
a. Obtain the mean and variance of the daily sales.
b. If the porfit can be described by the equation, profit= -10+(4*X)
What is the expected daily profit? What is the variance of the daily profit?