 
Summary: HOMEWORK SOLUTIONS FOR MATH 5651
HOMEWORK FOR WEEK 3 OF FALL 2011
Text: DeGroot and Schervish, 4rd edition
Assignment: §2.1: 7,8,9,14; §2.2: 5,6,7,10,12; §2.3: 3,5,7,13; §2.5: 10,24
Problem 7 of §2.1
Let A (resp., B, C) stand for the event that a randomly chosen family subscribes
to newspaper A (resp., B, C). We are asked to calculate Pr(BA). Well, using the
data in Problem 2 of §1.10, we have
Pr(BA) = Pr(AB)/ Pr(A) = .20/.60 = 1/3 = .333.
Problem 8 of §2.1
We keep the notation from the previous problem. We are asked to calculate
Pr(AA B C) =
Pr(A(A B C))
Pr(A B C)
=
Pr(A)
Pr(A B C)
.
Well, we are given Pr(A) = 0.6, and we know that Pr(A B C) = 0.85 because
that's the answer to problem 2 of §1.10 which was previously assigned as homework.
