In: Statistics and Probability
The following two-way contingency table gives the breakdown of the population of adults in a particular locale according to employment type and level of life insurance:
| 
 Level of Insurance  | 
|||
| 
 Employment Type  | 
 Low  | 
 Medium  | 
 High  | 
| 
 Unskilled  | 
 0.07  | 
 0.19  | 
 0.00  | 
| 
 Semi-skilled  | 
 0.04  | 
 0.28  | 
 0.08  | 
| 
 Skilled  | 
 0.03  | 
 0.18  | 
 0.05  | 
| 
 Professional  | 
 0.01  | 
 0.05  | 
 0.02  | 
An adult is selected at random. Find each of the following
probabilities.
a. The person has a high level of life insurance.
b. The person has a high level of life insurance, given that he
does not have a professional position.
c. The person has a high level of life insurance, given that he has
a professional position.
d. Determine whether or not the events “has a high level of life
insurance” and “has a professional position” are independent.
Solution :
Probability of an event E is given by,
a) P(high) = (0.00 + 0.08 + 0.05 + 0.02)
P(high) = 0.15
Hence, the probability that a randomly selected adult has a high level of insurance is 0.15.
b) We have to find P(high | not professional)







Hence, the probability that The person has a high level of life insurance, given that he does not have a professional position is 0.1413.
c) We have to find P(high | professional)





Hence, the probability that The person has a high level of life insurance, given that he has a professional position is 0.25.
d) Two events "“has a high level of life insurance” and “has a professional position" are said to be independent iff,
P(high and professional) = P(high).P(professional)
We have,
P(high and professional) = 0.02
P(high) = 0.15
P(professional) = 0.05
P(high).P(professional) = (0.15 × 0.05) = 0.0075

Hence, the events has a high level of life insurance” and “has a professional position” are not independent.