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- 2011-7-11
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2#
发表于 2011-7-13 16:27
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sgupta0827 Wrote:
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> Explanation of this question does not give me an
> idea about how to approach it. I mean, looking at
> the question or wording, how to figure out how to
> start on solving this question?
>
> In fact, I am little shaky on the
> fundamentals(Bayes formula) being used. Is there
> any other approach to solve it? Or, worse, this
> can not be solved by any other approach at all? I
> normally try to approach these kind of questions
> by condition probability(probably missing the DO
> NOT ENTER sign) as I can't figure out this has to
> be done using Bayes formula. Can you guys tell me
> how you guys approach this question?
>
> Cheryl Smith, CFA, conducts study comparing
> dividend changes for energy and non energy
> companies. Smith determines that 15% of the stock
> market universe consists of energy companies.
> Smith also determines that the probability that an
> energy company will increase its dividend is 90%
> and the probability that a non energy company will
> increase its dividend is 30%. After conducting her
> analysis, Smith randomly selects one company from
> the universe of stocks from the most recent
> quarter and notices that the company declared a
> dividend increase. The probability that Smith
> randomly selected an energy company is closest
> to:
> A. 5%
> B. 15%
> C. 35%
Use the tree... you get answer in seconds.. I dont know how to draw it here but
make two nodes - 0.15energy and 0.85 non energy
.15 energy node splits into two - inc .9 and dec .1
.85 non energy splits into two - inc .3 and dec .7
So total probability of inc is .9*.15 + .3*.85
Probability of energy out of this is .9*.15
you get 34.6% |
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