Recent content by neubreed

4,000 people are ill, 96,000 are healthy. out of the 4,000 3,600 will get a positive result. out of the 96,000 9,600 will get a positive result. I can do ratios, but I don't really understand how this helps me. I just need to know how to plug the right numbers into the probability theorems...

Any suggestions? This is due in a couple of hours... :( I don't understand how to make the calculations without knowing either the p of A given B or vice versa.

Right, yeah, I just realized that I've been calculating the givens incorrectly, that's where my issue is...

On second thought, it turns out that I solved a as though the events were independent, which they weren't... so the p(A given B)=p(A&B) / p(B) but p(A&B)= p(A) x P(B given A) I'm lost. I don't have either of the given probabilities, how can I solve the problem?? I had originally written 0.04...

so b actually turned out to be pretty simple and I'm certain of the answer, but a... i can't figure out whether it would be: (0.04)(0.9 x 0.04 / 0.04) + 0.96(0.9 x 0.96 / 0.96) or just (0.9 x 0.04 / 0.04) + (0.9 x 0.96 / 0.96)

Homework Statement The test for an illness is 90% accurate (meaning it gives a positive result 90% of the time if the patient has gingivitis and a negative reading 90% of the time if the patient doesn't). 4% of all people have this illness. a) calculate the probability the test will be...

I'm leaning towards adding, but the end result seems a little high... Would 624/1225 be the asnwer?

Homework Statement 26 out of 50 total students are tall. If 2 different students are called on at random, what is the probability that exactly one is tall? Homework Equations please see below The Attempt at a Solution so here's what I ended up with: 1st student is tall: 26/50 x...