Answer:
Step-by-step explanation:
Given that the profit the company makes on each customer visit is $0.75 per DVD minus $0.05 "fixed costs."
i.e. Profit
= P(x) = 0.75 x - 0.05 where x is the no of dvds sold
E(x) = [tex]E(0.75x-0.05)\\= E(0.75x) -E(0.05)\\= 0.75E(x) -0.05[/tex]
(using linear transformation rules for mean)
VarP(x) = [tex]Var(0.75 x - 0.05)\\= Var(0.75x)\\= 0.75^2 Var(x)[/tex]
Hence std dev P(X) = 0.75 std dev (x)