Jason inherited a piece of land from his great-uncle. Owners in the area claim that there is a 45% chance that the land has oil. Jason decides to test the land for oil. He buys a kit that claims to have an 80% accuracy rate of indicating oil in the soil. If the test predicts that there is no oil, what is the probability after the test that the land has oil?

A)0.1698
B)0.2217
C)0.5532
D)0.7660
Its not C

Question

Jason inherited a piece of land from his great-uncle. Owners in the area claim that there is a 45% chance that the land has oil. Jason decides to test the land for oil. He buys a kit that claims to have an 80% accuracy rate of indicating oil in the soil. If the test predicts that there is no oil, what is the probability after the test that the land has oil?

A)0.1698
B)0.2217
C)0.5532
D)0.7660
Its not C

tkhunny · Answer

#1 This is a silly question.  The probability the land has oil is independent of any testing.

#2 This is a silly question.  It is a rare test, indeed, that predicts "oil" with the same accuracy that it predicts "no oil".  Both probabilities should be specified.  I guess we are to assume 80/20 in both cases.

#3 Build a tree diagram.

anonymous · Answer

i figured it out but thankss @tkhunny

tkhunny · Answer

You're not going to share?

anonymous · Answer

it wa A) 0.1698 @tkhunny