Probability & Statistics Ch.2 Section 1 Question 3

· Mohammad-Ali Bandzar

Solutions for “Probability and Statistics: The Science of Uncertainty” (Second Edition). These are solutions I have come up with; I offer no guarantee of accuracy.

Question

Let S={1,2,3,4,5}S=\{1,2,3,4,5\}.

a) Define two different (i.e., nonequal) nonconstant random variables X and Y on S.

b) For the random variables X and Y that you have chosen, let Z=X+Y2Z=X+Y^2. Compute Z(s)Z(s) for all sSs\in S.

Solution

There are infinitely many possible solutions; below is just one I came up with.

(a) Define two different nonconstant random variables X and Y on S

Let X(s)=s+1X(s)=s+1 and Y(s)=s+2Y(s)=s+2

(b) Let Z=X+Y2Z=X+Y^2. Compute Z(s)Z(s) for all sSs\in S

Z(1)=(s+1)+(s+2)2=2+(3)2=11Z(1)=(s+1)+(s+2)^2 = 2+(3)^2 = 11

Z(2)=(s+1)+(s+2)2=3+(4)2=19Z(2)=(s+1)+(s+2)^2 = 3+(4)^2 = 19

Z(3)=(s+1)+(s+2)2=4+(5)2=29Z(3)=(s+1)+(s+2)^2 = 4+(5)^2 = 29

Z(4)=(s+1)+(s+2)2=5+(6)2=41Z(4)=(s+1)+(s+2)^2 = 5+(6)^2 = 41

Z(5)=(s+1)+(s+2)2=6+(7)2=55Z(5)=(s+1)+(s+2)^2 = 6+(7)^2 = 55