# math

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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 -

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.

• math--why not? -

have an "answering machine" also has call waiting?

• math -

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

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