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Parillamaster
01-31-2006, 01:26 PM
2001 NCAA Poll
Will Big 10 or Pac 10 have a team in the Rose Bowl?
13,429 respondents
2961 said Big 10
4494 said Pac 10
6823 said neither

What I have done:
B=Big 10
P=Pac 10
N=Neither Big 10 nor Pac 10
r=respondents

Probability Points: xi/r
B= 2961/13429= .22
P= 4494/13429= .33
N= 6823/13429= .55

Question A:
Probability of Neither = .55

Question B: not sure if this is right?
Probability of B or P = P(B) + P(P)
Probability of B or P = .22 + .33
Probability of B or P = .55

Question C: Need help
Probability of both B and P?

Thanks,
ParillaMaster

JohnM
01-31-2006, 01:47 PM
Questions B and C can be answered together.

P(B or P) = P(B) + P(P) - P(B and P)

P(B or P) = 1 - P(not B and not P)
is the same as saying P(B or P) = 1 - P(neither)
so, P(B or P) = 1 - .55 = .45

Now,
P(B or P) = P(B) + P(P) - P(B and P)
.45 = .22 + .33 - P(B and P)
.45 = .55 - P(B and P)
P(B and P) = .10

Parillamaster
02-02-2006, 09:27 AM
Thanks for the help JohnM