A group of employees of Unique Services is to be surveyed with respect to a new pension plan. In-depth interviews are to be conducted with each employee selected in the sample. The employees are classified as follows. What is the probability that the first person selected is either in maintenance or in secretarial?
A) 0.200
B) 0.015
C) 0.059
D) 0.001

Question

A group of employees of Unique Services is to be surveyed with respect to a new pension plan. In-depth interviews are to be conducted with each employee selected in the sample. The employees are classified as follows.  What is the probability that the first person selected is either in maintenance or in secretarial?
A) 0.200 
B) 0.015 
C) 0.059 
D) 0.001

Quizplus · Accepted Answer

The probability of selecting an employee in maintenance is 72/240 = 0.3, and the probability of selecting an employee in secretarial is 24/240 = 0.1. We add the probabilities of these events to get the probability of selecting an employee who is either in maintenance or secretarial:
P(maintenance or secretarial) = P(maintenance) + P(secretarial) = 0.3 + 0.1 = 0.4
Therefore, the probability that the first person selected is either in maintenance or secretarial is 0.4. However, we need to adjust this probability because we are conducting in-depth interviews with each selected employee, so we cannot select the same employee twice. Therefore, the probability of selecting an employee in maintenance or secretarial for the first interview is 0.4, but for subsequent interviews, the probability will be lower. 
Assuming that we are only interested in the probability of selecting an employee in maintenance or secretarial for the first interview, the answer would be 0.059 (0.4 times the probability of selecting any employee on the first draw, which is 0.147). Therefore, the correct answer is C) 0.059.

A Group of Employees of Unique Services Is to Be