Independent solution

How to solve this Discrete Random Variables question

Setup

Setup

Let F and R be the two annual treatment counts. First calculate their expected values from the supplied mass functions.

E[F]=0(0.60)+1(0.20)+2(0.15)+3(0.05)=0.65E[F]=0(0.60)+1(0.20)+2(0.15)+3(0.05)=0.65
E[R]=0(0.80)+1(0.20)=0.20E[R]=0(0.80)+1(0.20)=0.20

Model

Model

The annual benefit is the sum of the fully covered lower-cost treatment and the partially covered higher-cost treatment.

C=50F+0.70(500)R=50F+350RC=50F+0.70(500)R=50F+350R

Compute

Compute

Apply linearity; no assumption about dependence between the two counts is needed.

E[C]=50E[F]+350E[R]E[C]=50E[F]+350E[R]
=50(0.65)+350(0.20)=32.50+70.00=102.50=50(0.65)+350(0.20)=32.50+70.00=102.50

Answer

Answer

The expected annual payment is 102.50.

102.50(B)\boxed{102.50\quad\text{(B)}}