300 400 400 500 Unit Demand Probability X f x 500 600 Here the random variable x is represented by the unit demand 600 Step 2 The random variable x in this distribution is represented by the unit demand column and the probability f x in this distribution is represented by the probability column Complete the table by multiplying each value of the random variable by its respective probability The expected value will be the sum of these values 0 35 0 15 0 15 0 30 0 30 0 20 0 20 xf x 300 0 35 E x xf x Therefore the monthly order should be unit demand column and f x is represented by the probability units probability column