An employee's office window overlooks a busy four-way stop, and the employee decides to track, per minute, the number of drivers who fail to stop. From data taken over many randomly selected times, the employee gets this probability model:

The expected number of drivers failing to stop, per minute, is:
A) 0.5.
B) 2.2.
C)2)
D)3)
E) varies from minute to minute.

Question

An employee's office window overlooks a busy four-way stop, and the employee decides to track, per minute, the number of drivers who fail to stop. From data taken over many randomly selected times, the employee gets this probability model:

The expected number of drivers failing to stop, per minute, is:

The expected number of drivers failing to stop, per minute, is:
A) 0.5. 
B) 2.2. 
C)2) 
D)3) 
E) varies from minute to minute.

Quizplus · Accepted Answer

To find the expected number of drivers failing to stop per minute, we need to find the weighted average of the number of drivers failing to stop and their probabilities.

Expected number of drivers failing to stop = (0 x 0.6) + (1 x 0.3) + (2 x 0.1) = 0 + 0.3 + 0.2 = 0.5 + 0.2 = 2.2

Therefore, the expected number of drivers failing to stop per minute is 2.2, and the best choice is B.

An Employee's Office Window Overlooks a Busy Four-Way Stop, and the Employee