Question

A certain factory operates three different shifts. Over the last year, 200 accidents have occurred at the factory. Some of these can be attributed at least in part to unsafe working conditions, whereas the others are unrelated to working conditions. The accompanying table gives the percentage of accidents falling in each type of accident-shift category.

		Unsafe Conditions	Unrelated to Conditions
	Day	12%	29%
Shift	Swing	6%	14%
	Night	5%	34%

Suppose one of the 200 accident reports is randomly selected from a file of reports, and the shift and type of accident are determined.

(a) What are the simple events? (Let S₁, S₂, and S₃ represent the day, swing, and night shifts, respectively. Let C₁ and C₂ represent the unsafe conditions and unrelated to conditions, respectively. Enter your answer in set notation.)

(b) What is the probability that the selected accident was attributed to unsafe conditions?


(c) What is the probability that the selected accident did not occur on the day shift?

Answer 1

a) The simple events are - type of shifts and type of accidents

b) The probability that the selected accident was attributed to unsafe conditions

c) The probability that the selected accident did not occur on the day shift

= P(selected accident occurred on the swing shift) + P(selected accident occurred on the night shift)