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by dtweah » Sun Mar 07, 2010 1:08 pm
A box contains 4 fair coins and 6 biased coins. Whenever a fair coin is
fipped, it comes up heads with probability 0:5. Whenever a biased coin
is ipped, it comes up heads with probability 0:8. A coin is randomly
chosen from the box and then ipped. What is the probability that it
will come up heads?

(a) 0:6
(b) 0:64
(c) 0:68
d) 0:72
(e) 0:76
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by firdaus117 » Sun Mar 07, 2010 9:40 pm
probability that it will come up heads=(Probability of selecting a fair coin X Probability of getting head on a fair coin)+(Probability of selecting a biased coin X Probability of getting head on a biased coin)
[spoiler] =0.4*0.5+0.6*0.8
=0.2+0.48
=0.68 Option C[/spoiler]
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