Question

Kevin’s family has a history of diabetes. The probability that Kevin would inherit this disease is 0.75. Kevin decides to take a test to check if he has the disease. The accuracy of this test is 0.85. What is the probability that Kevin has diabetes and the test predicts this?

Answer 1

(A).0375, (B).1125, (C).2125, (D).6375, (E).8725

Answer 2

if A and B are two independent events, then
P(A∩B) = P(A)xP(B)

here the probability that kevin inherits the disease and the accuracy of the test are independent

so the intersection of the two probabilities = ?

Answer 3

.6375 ?

Answer 4

correct

Answer 5

Thank @hoblos i was just second guessing myself.

Answer 6

any time :)

Answer 7

Kevin’s family has a history of diabetes. The probability that Kevin would inherit this disease is 0.75. Kevin decides to take a test to check if he has the disease. The accuracy of this test is 0.85

Answer 8

We now know that the test predicted that Kevin does not have the disease. Using this information, calculate the probability that Kevin does not have diabetes after the test was taken.

Answer 9

@hoblos could you help me again?

Answer 10

in general \[P(A|B) = \frac{ P(A∩B) }{ P(B) }\]

here, A is the event that kevin doesn't have diabetes
and B is the accuracy of the test

so let's do it by steps
if probability of having diabetes is 0.75
the probability of not having diabetes is ?

Answer 11

.25

Answer 12

correct, so \[P(A∩B) = ?\]

Answer 13

.2125 ?

Answer 14

By the way, whats that symbol mean in the middle a and b?

Answer 15

it's intersection
it means the intersection between the two events
and .2125 is correct

Answer 16

now we need P(A|B)

Answer 17

O OK. .6375 ?

Answer 18

how did you get that ?

Answer 19

woops(: is .2125 correct for P(A|B)?

Answer 20

P(A∩B) = .2125

P(A|B) = P(A∩B) over P(B) = ?

Answer 21

P(B) is the accuracy .85

Answer 22

I divided .2125 by .85 and got .25?

Answer 23

yeah correct

Answer 24

Now, what is the next step?

Answer 25

that's what we need

Answer 26

I haven't seen us discuss the answer yet.

Answer 27

you need a discussion for the answer ?

Answer 28

No, i just havent seen it yet.
(A).0925, (B).3565, (C).4827, (D).6538, (E).8765

Answer 29

These are my multiple choices. I don't think I've see one come up from what we've worked on.

Answer 30

umm we may have been wrong somewhere i'll try to figure it out
give me a second

Answer 31

Yes, thank you.

Answer 32

im confused about that !
@ganeshie8 can you help ?

Answer 33

Either way thanks for the help, i'm done for the day in about 20 minutes. So whatever works(:

Answer 34

@Mr.Man420 try posting the second question as a new question so that somebody may see it and try to help

Answer 35

Ok will do.

Answer 36

for the last question...
http://www.wolframalpha.com/input/?i=%280.25*0.85%29%2F%280.75*0.15+%2B+0.25*0.85%29

Answer 37

above link is for P("no diabetes" | "test is negative")

Answer 38

Thank you both i really appreciate it @ganeshie8 @hoblos !!