Answer:
3. What is the probability that an adult selected at random has both a landline and a cell phone?
A. 0.58
4. Given an adult has a cell phone, what is the probability he does not have a landline?
C. 0.3012
Step-by-step explanation:
We solve this problem building the Venn's diagram of these probabilities.
I am going to say that:
A is the probability that an adult has a landline at his residence.
B is the probability that an adult has a cell phone.
C is the probability that a mean is neither of those.
We have that:
In which a is the probability that an adult has a landline but not a cell phone and 
is the probability that an adult has both of these things.
By the same logic, we have that:
The sum of all the subsets is 1:
2% of adults have neither a cell phone nor a landline.
This means that 
.
73% of adults have a landline at their residence (event A); 83% have a cell phone (event B)
So 
.
What is the probability that an adult selected at random has both a landline and a cell phone?
This is .
We have that 
. So
By the same logic, we have that:
.
So
So the answer for question 3 is A.
4. Given an adult has a cell phone, what is the probability he does not have a landline?
83% of the adults have a cellphone.
We have that
25% of those do not have a landline.
So 
The answer for question 4 is C.
