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?