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Unformatted text preview: ine the value of p (You will not be able to draw the whole tree, since it
is inﬁnitely large. Just draw the part you need to solve the problem.)
The basic idea of this problem is to ﬁgure out a way how we get exactly two “good day” messages. 2 p start 1p 0.4 B 0.6 0.6 B 0.4 B1
B1 B2
B2 There are two possibilities for exactly two “good day” messages:
• B true, B1 true, B1 true, B1 false =: way 1
• B false, B2 true, B2 true, B2 false =: way 2
The probabilities for each of the ways are:
P ( way 1 ) = p · 2/5 · 2/5 · 3/5 = p · P ( way 2 ) = 12
125 (1 − p) · 3/5 · 3/5 · 2/5 = (1 − p) · 0.4
0.6
0.6
0.4 B1
B1
B2
B2 0.4
0.6 0.6
0.4 B1
B1 B2
B2 18
125 Therefore
3/25 = P ( “exactly 3...
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This homework help was uploaded on 03/11/2014 for the course STAT 330 taught by Professor Staff during the Spring '08 term at Iowa State.
 Spring '08
 Staff

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