Nathan had an infection, and his doctor wanted him to take penicillin. Because Nathan’s father and paternal grandfather were allergic to penicillin, Nathan has a 75% chance of having the same allergy. The doctor performed a skin test to see whether Nathan would react to it. The test is 98% accurate. If the test predicts that Nathan is not allergic to penicillin, what is the probability after the test that Nathan is not allergic to the drug?

0.1135

0.2450

0.9423

0.9932

Question

Nathan had an infection, and his doctor wanted him to take penicillin. Because Nathan’s father and paternal grandfather were allergic to penicillin, Nathan has a 75% chance of having the same allergy. The doctor performed a skin test to see whether Nathan would react to it. The test is 98% accurate. If the test predicts that Nathan is not allergic to penicillin, what is the probability after the test that Nathan is not allergic to the drug?

0.1135

0.2450

0.9423

0.9932

anonymous · Answer

@tkhunny  @cherry18

anonymous · Answer

0.25 x 0.98 = 0.2450 .

anonymous · Answer

B then. Sorry 'bout that

tkhunny · Answer

NO, no...  Draw the 2x2 grid.

p(Not Allergic|Positive Test)

anonymous · Answer

Huh? 2x2 grid...you need a matrix for this problem?

tkhunny · Answer

That depends on if you want to see the entire situation.  If you want to rush through it and hope you got everything, feel free to go some other way.