Let X represent the number of tires with low air pressure on a randomly chosen car.
a. Which of the three functions below is a possible probability mass function of X? Explain.
b. For the possible probability mass function, compute μX and .
Solution:
Step 1 of 3:
Let X denote the number of tires with low air pressure on a randomly chosen car.
X 

0 
1 
2 
3 
4 

0.2 
0.2 
0.3 
0.1 
0.1 

(x) 
0.1 
0.3 
0.3 
0.3 
0.2 
(x) 
0.1 
0.2 
0.2 
0.4 
0.1 
We have to find
 Which of given three functions is a possible probability mass function of X.
 For the possible mass function,we have to compute E(x) and V(X).