Problems? Is your data what you think it is? PerlMonks

### comment on

 Need Help??
Hi, your link to the puzzle has to be updated, it now points to a nonexistent page.

Nevertheless, I found the solution and also this discussion about the problem, but the solution is flawed IMHO. Apart from the fact that the author is arguing about the phrasing in the original solution, the algebra should be the following (quoted from one of the messages in the thread):

```P(correct guess) =
P(we were shown the higher number H)
* P(we guessed "high" given H)
+ P(we were shown the lower number L)
* P(we guessed "low" given L)

=> (plugging in from the original selection method)

P(correct guess) = (1/2) * (1 - F(H)) + (1/2) * F(L)

=>

P(correct guess) = (1/2) (1 - (F(H) - F(L)))

=> Since F(H) - F(L) > 0 (by assumption)

P(correct guess) = (1/2) (1 - (a positive value))

=>

Therefore,

P(correct guess) < 1/2.
What I find very amusing is that we're using two different values (namely H and L) to feed the F function, but this is not applicable. We have to use the same value - that is the value we figure out in our mind, let's call it y. This leads to:
```P(correct guess) = (1/2) (1 - (F(y) - F(y))) = 1/2
as it should clearly be.

Flavio
perl -ple'\$_=reverse' <<<ti.xittelop@oivalf

Don't fool yourself.

In reply to Re: Spooky math problem by polettix
in thread Spooky math problem by tilly

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or or How to display code and escape characters are good places to start.

Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others making s'mores by the fire in the courtyard of the Monastery: (3)
As of 2022-05-23 00:23 GMT
Sections?
Information?
Find Nodes?
Leftovers?
Voting Booth?
Do you prefer to work remotely?

Results (81 votes). Check out past polls.

Notices?