Is there more context to the question?
Answer:
B.) 18
Step-by-step explanation:
To find the correct b value we use this formula
b² - 4ac = 0
b = What we are solving for
a = 1
c = 81
b² - 4(1)(81) = 0
b² - 324 = 0
b² = 324

b = ±18
And 18 is one of the answer choices
So B.) 18 is the correct answer.
Answer: Its b also y u test so ez what grade u in lol?
Answer:
There is a 2.17% probability that a randomly selected person aged 40 years or older is male and jogs.
It would be unusual to randomly select a person aged 40 years or older who is male and jogs.
Step-by-step explanation:
We have these following probabilities.
A 13.9% probability that a randomly selected person aged 40 years or older is a jogger, so
.
In addition, there is a 15.6% probability that a randomly selected person aged 40 years or older is male comma given that he or she jogs. I am going to say that P(B) is the probability that is a male.
is the probability that the person is a male, given that he/she jogs. So 
The Bayes theorem states that:

In which
is the probability that the person does both thigs, so, in this problem, the probability that a randomly selected person aged 40 years or older is male and jogs.
So

There is a 2.17% probability that a randomly selected person aged 40 years or older is male and jogs.
A probability is unusual when it is smaller than 5%.
So it would be unusual to randomly select a person aged 40 years or older who is male and jogs.