Dear co-listers. I was solving some exercises on probability topics, but
suddenly a doubt came to me when I tried to solve a problem.
The problem says that: Suppose that the probability of being sick of flu
during an epidemic is 0.6. The past experience has showed that certain serum
is effective in 80% of the times to avoid a person being sick of flu, if the
person is exposed to it. Two people, one inoculated and the other don’t are
employees of a company. Suppose that they aren’t in the same place, they are
not in contact with the same people and they can’t be infected between each
other. What is the probability that at least one of them is affected by the
flu?
I make the following reasoning:
Non-inoculated sick, inoculated non-sick: 0.6 X 0.8 = 0.48
Non-Inoculated non-sick, inoculated sick: 0.4 X 0.2 = 0.08
Both Sick: 0.6 X 0.2 = 0.12
Answer: 0.68. I don’t know if the procedure and reasoning are wrong, but the
textbook says that the answer (without explaing how they get it) is 0.5952.
Can somebody provide me advice to this respect?
Thanks for your kindly cooperation.
_________________________________
Rodrigo Briceño
Consultor
Sanigest International
San José, Costa Rica
Telf. (506) 291-1200, ext.118
Fax. (506) 232-0830
Cell (506) 357-4535
www.sanigest.com
Apdo. 23-2015 Zapote Costa Rica
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