Rick is taking a math course and an English course. The probabilities for Rick getting an A in his math course and English course are .6 and .8 respectively. The probability of getting an A in either math or English is .9.
a. What is the probability that Rick gets an A in both courses?
b. What is the probability that Rick will not get an A in either of the two courses?
2007-05-02 17:28:57 · 3 answers · asked by kitty 1 in Science & Mathematics ➔ Mathematics
a. P(A and B) = P(A) + P(B) - P(A or B)
P(A and B) = .6 + .8 - .9
P(A and B) = .5
b. P(Ac and Bc) = 1 - P(A or B)
P(Ac and Bc) = 1 - .9
P(Ac and Bc) = .1
2007-05-02 17:37:23 · answer #1 · answered by iamaspursfanatic 3 · 1⤊ 0⤋
The given probabilities of getting an A are:
P(M) = probability of getting an A in math
P(E) = probability of getting an A in English
P(M) = 0.6
P(E) = 0.8
P(M U E) = 0.9
a. What is the probability that Rick gets an A in both courses?
Find P(M ∩ E).
P(M ∩ E) = P(A) + P(E) - P(M U E) = 0.6 + 0.8 - 0.9 = 0.5
b. What is the probability that Rick will not get an A in either of the two courses?
P(No A) = 1 - P(M U E) = 1 - 0.9 = 0.1
2007-05-02 18:22:45 · answer #2 · answered by Northstar 7 · 1⤊ 0⤋
a. .6 * .8 = .48
b. 1 - .9 = .1
2007-05-02 17:32:00 · answer #3 · answered by gohawk4 2 · 0⤊ 3⤋