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help with some math problems, please?
1. Let A and B be events in a sample space S such that P(A) = 0.37, P(B) = 0.49 and P(A ∩ B) = 0.17. Find P(A | B).
a) 0.0204
b) 0.4595
c) 0.1977
d) 0.3469
e) 0.7551
f) None of the above.
2. Let A and B be events in a sample space S such that P(A) = 27⁄100 , P(B) = 49⁄100 , and P(A ∩ B) = 7⁄100 . Find P(B | Ac ).
a) 0.8571
b) 0.0959
c) 0.5753
d) 1.8148
e) 0.6712
f) None of the above.
3. Suppose that A and B are independent events. If P(A) = 7⁄10 and P(B) = 3⁄5 , find P(A ∩ B).
a) 0.06
b) 1.00
c) 0.42
d) 0.07
e) 0.13
f) None of the above.
4. Quality Control: A company has four photocopy machines A, B, C and D. The probability that a given machine will break down on a particular day is
P(A) = 13⁄100
P(B) = 9⁄50
P(C) = 1⁄5
P(D) = 13⁄100
Assuming independence, what is the probability on a particular day that all machines will break down?
a) 0.00164366
b) 0.00060840
c) 0.01000000
d) 0.00000234
e) 0.16436555
f) None of the above.
1 Answer
- SqdancefanLv 78 years agoFavorite Answer
1. P(A | B) = P(A ∩ B)/P(B)
2. Assuming Ac is the complement of A,
.. P(Ac) = 1 - P(A)
.. P(B ∩ Ac) = P(B) - P(A ∩ B)
.. P(B | Ac ) = P(B ∩ Ac)/P(Ac) ... same conditional probability formula as in problem 1.
3. P(A ∩ B) = P(A)*P(B) ... when A and B are independent
4. P(A ∩ B ∩ C ∩ D) = P(A)*P(B)*P(C)*P(D) ... when all are independent