+0  
 
+3
732
8
avatar+1760 

Carson flips over the cards of a standard 52-card deck one at a time. What is the probability that he flips over the ace of spades before any face card (jack, queen or king)?

Mellie  Apr 18, 2015

Best Answer 

 #5
avatar+26322 
+13

I just used MathCad to work out your expression Melody.  

Alan  Apr 18, 2015
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8+0 Answers

 #1
avatar+90988 
+13

This is what I have come up with.  :/   [no guarantees that it is correct though]

Where on Earth are you digging these questions up from Mellie. :))

 

Now I have to work out how to calculate this without doing every bit separately.

Got any ideas Alan?  Do you know how to get the web2 calc to do the numerator?

 

$$\displaystyle\sum_{x=1}^{40}\left(\frac{39!}{(40-x)!}\times(52-x)!\right)\div 52!$$

Melody  Apr 18, 2015
 #2
avatar+1760 
+3

I got it, it is 1/13. i lost the solution.

Mellie  Apr 18, 2015
 #3
avatar+26322 
+10

There is 1 ace of spades and there are 12 face cards.  The other 39 cards are irrelevant!  So this reduces to the probability of choosing the ace of spades first out of a pack of 13.  This probability is just 1/13.

 

As it happens, Melody, your complicated expression evaluates to 1/13.

Alan  Apr 18, 2015
 #4
avatar+90988 
+5

Thanks Alan that makes sense.   

 

How did you work out my expression?

Melody  Apr 18, 2015
 #5
avatar+26322 
+13
Best Answer

I just used MathCad to work out your expression Melody.  

Alan  Apr 18, 2015
 #6
avatar+90988 
+8

ok thanks Alan :)

Melody  Apr 18, 2015
 #7
avatar+1035 
+5

Melody, if you like doing the Rube Goldberg of math equations, this script will solve it for you.

 

sum ((39!*(52-i)!)/(40-i)!) /(52!) from i=1 to 40

Click here to execute Melody’s Rube Goldberg math script

 

Here are some cool Rube Goldberg contraption videos

 

2014 winner Rube Goldberg contest

https://www.youtube.com/watch?v=uF3nV0r87v8

 

London's Science Museum most elaborate Rube Goldberg machine, "On The Move"

https://www.youtube.com/watch?v=JmnRJ2M4eik

Nauseated  Apr 21, 2015
 #8
avatar+90988 
+5

Thanks Nauseated :))

"An intentionally delightful waste time and effort"  I love it.

That is what I do with my time Folks.   Isn't that a wonderful description.  :))

 

These Rude Goldburg displays are definitely worth the watch.   :))

Thanks for the Wolfram|Alpha solution too.   

Melody  Apr 21, 2015

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