Allergic reactions to poison ivy can be miserable. Plant oils cause the reaction. Researchers at Allergy Institute did a study to determine the effects of washing the oil off within 5 minutes of exposure. A random sample of 1000 people with known allergi poison ivy participated in the study. Oil from the poison ivy plant was rubbed on a patch of skin. For 500 of the subjects, it was washed off within 5 minutes. For the other 500 subjects, the oil was washed off after 5 minutes. The results are summarize following table. Reaction None Mild Strong Column Total P(M) P(S) Within 5 Minutes After 5 Minutes 420 55 25 500 Let's use the following notation for the various events: W = washing oil off within 5 minutes, A = washing oil off after 5 minutes, N = no reaction, M = mild reaction, S = strong reaction. Find the following probabilities for a person selected at random f sample of 1000 subjects. (Use 3 decimal places.) (a) P(N) (b) P(NIW) P(SW) (c) P(NIA) P(SA) (d) P(N and W) P(M and W) Row Total 460 403 137 1000 40 348 112 500
Allergic reactions to poison ivy can be miserable. Plant oils cause the reaction. Researchers at Allergy Institute did a study to determine the effects of washing the oil off within 5 minutes of exposure. A random sample of 1000 people with known allergi poison ivy participated in the study. Oil from the poison ivy plant was rubbed on a patch of skin. For 500 of the subjects, it was washed off within 5 minutes. For the other 500 subjects, the oil was washed off after 5 minutes. The results are summarize following table. Reaction None Mild Strong Column Total P(M) P(S) Within 5 Minutes After 5 Minutes 420 55 25 500 Let's use the following notation for the various events: W = washing oil off within 5 minutes, A = washing oil off after 5 minutes, N = no reaction, M = mild reaction, S = strong reaction. Find the following probabilities for a person selected at random f sample of 1000 subjects. (Use 3 decimal places.) (a) P(N) (b) P(NIW) P(SW) (c) P(NIA) P(SA) (d) P(N and W) P(M and W) Row Total 460 403 137 1000 40 348 112 500
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Transcribed Image Text:Allergic reactions to poison ivy can be miserable. Plant oils cause the reaction. Researchers at Allergy Institute did a study to determine the effects of washing the oil off within 5 minutes of exposure. A random sample of 1000 people with known allergies to
poison ivy participated in the study. Oil from the poison ivy plant was rubbed on a patch of skin. For 500 of the subjects, it was washed off within 5 minutes. For the other 500 subjects, the oil was washed off after 5 minutes. The results are summarized in the
following table.
Within 5 Minutes
420
55
25
500
Let's use the following notation for the various events: W = washing oil off within 5 minutes, A = washing oil off after 5 minutes, N = no reaction, M = mild reaction, S = strong reaction. Find the following probabilities for a person selected at random from this
sample of 1000 subjects. (Use 3 decimal places.)
(a) P(N)
P(M)
P(S)
Reaction
None
Mild
Strong
Column Total
(b) P(N | W)
P(S | W)
(c) P(NA)
P(S | A)
(d) P(Na W)
P(M and W)
After 5 Minutes
40
348
112
500
(e) P(N or M).
Row Total
460
403
137
1000
Are the events N = no reaction and M = mild reaction mutually exclusive? Explain.
O No. P(N and M) = 0.
O Yes. P(N or M) = 0.
O No. P(N or M) * 0.
O Yes. P(N and M) = 0.
(f) Are the events N = no reaction and W = washing oil off within 5 minutes independent? Explain.
O No. P(N and W) = P(N) P(W).
O Yes. P(N and W) P(N) P(W).
O Yes. P(N and W) = P(N) P(W).
O No. P(N and W) P(N) P(W).
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