.
About 18% of the population of a large country is nervous around strangers.
If two people are randomly selected, what is the probability
(a) what is the probability both are nervous around strangers?
(b) What is the probability at least one is nervous around strangers?
Assume the events are independent.
~~~~~~~~~~~~~~~~~~
(a) P = 0.18*0.18 = 0.0324. ANSWER
(b) P = 1 - (1-0.18)*(1-0.18) = 1 - 0.82*0.82 = 0.3276. ANSWER
Here 1-0.18 = 0.82 is the probability that a randomly selected person is not nervous about strangers.
and the product 0.82*0.82 is the probability that two randomly selected persons are not nervous about strangers.
So, the complement 1 - 0.82^2 is the probability that at least one of two is nervous.
Solved.