Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Math Topics » geometry.pre-college.independent

Topic: geometric probability
Replies: 0  

Advanced Search

Back to Topic List Back to Topic List  
Eileen Schoaff

Posts: 39
Registered: 12/3/04
geometric probability
Posted: Dec 4, 1996 11:59 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

>I recently used this problem from the NSML contest problem database.
>I can't seem to solve it directly. Any help on it would be
>appreciated!


>: an 8-ft stick and a 22-ft stick are both randomly broken into
>two parts. What is the probability that the longer part of the
>8-ft stick is longer than the shorter part of the 22-ft stick?
>


I like Gary Tupper's explanation of making the rectangle 4 x 11, but then he
seems to get confused and ended up with 8 in there somewhere.

May I suggest placing coordinates on the corners of the rectangle. The
coordinate (x,y) would represent x=length of short part of 22-ft stick, y=length
of long part of 8-ft stick. The rectangle would have vertices at (0,4), (0,8),
(11,4), and (11,8).
Then draw a segment representing where these lengths would be equal, from (4,4)
to (8,8).

-----------
| / |
| / |
| / |
| / |
-----------

I think this is what Gary meant. Now any point in the trapezoid to the left
has coordinates (x,y) where x<y. Area of trapezoid = 4*(4+8)/2 = 24. Area of
rectangle = 4*11 = 44, so probability is 24/44.

Gary obviously did better in geometric probability than he lets on, but he
needed a picture!

Eileen Schoaff
Buffalo State College






Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.