EXAMPLE 3.5.6

According to a study in 1992 by the U.S. Department of Agriculture, 80% of commercially grown celery samples and 45% of commercially grown lettuce samples contain traces of agricultural poisons (insecticides, herbicides, fungicides).

If Homer eats one serving (one sample) of celery and one serving of lettuce:

1. What is the probability that both the celery and the lettuce contain traces of agricultural poisons?

2. What is the probability that neither serving contains traces of agricultural poisons?

3. What is the probability that at least one of the servings contains traces of agricultural poisons?

SOLUTIONS

Let E be the event that the sample of celery has traces of poisons; then P(E) = .8. Let F be the event that the lettuce has traces of poisons; then P(F) = .45.

1.

2.

3.