Scenario 12.1 : Simon and Paula are walking home from school and come across a man being attacked by a crazed miniature poodle. It takes only one of them to save the man from the poodle, but since responsibility is diffuse, each is only 70% likely to try to rescue the man.
-Refer to Scenario 12.1. Suppose that a third friend, Ryan, joins Simon and Paula on their way home from school, and this reduces the probability of any particular individual from stepping forward to help the man being attacked from 70% to 60%. What is the probability of either Simon, Paula, Ryan, or any combination of the three trying to rescue the man?

Question

Quizplus · Accepted Answer

The probability of none of them stepping forward to help is calculated by multiplying the probabilities of each not helping (40% for each, since 100% - 60% = 40%). So, 0.4 * 0.4 * 0.4 = 0.064 or 6.4%. The probability of at least one of them stepping forward is the complement of this, which is 1 - 0.064 = 0.936 or 93.6%.