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Unformatted text preview: is the probability that exactly 4 sets detect the missile?
At least one set?
we can think of this setup as a Bernoulli sequence with 5 repetitions. Then, the probability that exactly
4 radar sets detect the missile is:
5
1 0.94 · 0.1 · = 0.32805. At least one set  we computed that probability before: 0.99999.
Let X be the number of times a keyword is found. Then
P (X ≥ 2) = P (X = 2) + P (X = 3) + P (X = 4)
and the probability to ﬁnd a keyword in exactly 2 databases out of a random four databases is
P (X = 2) = 5
2 4
2 · = 9
4 10 · 6
= 0.4762.
126 Similarly,
P (X = 3) = P (X = 4) = and P (X ≥ 2) = 105
126 5
3 · 4
1 9
4
5
4 · 4
0 9
4 = 10 · 4
= 0.3175
126 = 5
= 0.0397
126 = 0.8333. 4...
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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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