Posted by anonymous on .
If 90% of the households in a certain region have an answering machines and 50% have both answering machines and call waiting, what is the probability that a household chosen at random and found to have an answering machine also has call waiting?
This is what I think...(Am I correct?)
P(answering and call waiting/answering machine)=(.50/.90)=.56 or 56%

math 
bobpursley,
DIdn't the probem state that 50 percent have both? Am I missing something here?
I don't read a conditional probabality on the fifty percent. 
mathwhy not? 
anonymous,
have an "answering machine" also has call waiting?

math 
bobpursley,
OK,assumeing the problem statement is conditional, then you are correct. 56 percent of those who have answering machine have call waiting also.