Question

Giving a test to a group of students, the grades and gender are summarized below

	A	B	C	Total
Male	10	14	18	42
Female	19	11	15	45
Total	29	25	33	87

If one student is chosen at random,

Find the probability that the student was female AND got a "A".

Question 8 . 1 pts

A certain disease has an incidence rate of 0.8%. If the false negative rate is 8% and the false positive rate is 5%, compute the probability that a person who tests positive actually has the disease. round three decimal places.

Answer 1

1)

P( student was female AND got a "A".) =19/87

2)

P(tested positive)=P(have disease and tested positive)+P(not have disease and tested positive)
	=0.008*0.92+0.992*0.05=0.057

Therefore P(have disease|tested positive)=0.008*0.92/0.057=0.129