The NIH is creating a test for the Zika virus. The incidence of a Zika is low, 7 percent in the general population.  There is a trial version, but it sometimes misses the disease.  The probability of a false negative is 13 percent.  Similarly, someone who does not have Zika, will sometimes get a positive reading.  The probability of this is 20 percent.   Fill in the tree diagram and ...

Answer in percent to 2 decimal places.

	Marginal Probabilities		Conditional Probabilities		Joint Probabilities
			P(positive|D)		P(D and positive)
	%			False negative
	P(D)		P(negative|D)		P(D and negative)
				False Positive
	P(no D)		P(positive|no D)		P(no D and positive)
			P(negative|no D)		P(no D and negative)

Calculate the probability that a positive test result means someone has Zika. 

%