
Probability and Statistics Basic Probability and Statistics Math Forum 
 LinkBack  Thread Tools  Display Modes 
October 24th, 2017, 11:58 AM  #1 
Newbie Joined: Oct 2017 From: Hanoi Posts: 4 Thanks: 1  Probability of choosing an 'L' shape on a chess board
Someone up for checking my work? This is for fun, not homework. "Three squares are randomly chosen from an 8x8 chess board. What is the probability that they form an 'L' shape? " My process: First consider four contiguous squares that form a larger, 2x2 square. Choosing any three squares forms an 'L' shape, so each such square represents four L's. And there are 49 such distinct 2x2 squares on a chess board. So the number of possible L's is 196four L's per 2x2 square times 49 squares. All that remains then is to determine the entire overall probability space. That would be n choose k, n=3, and k = 64. Boil that down you get 41664 possible sets of 3 without respect to order. So, we have 196/41664 which is 7/1488. Did I do good? 
October 24th, 2017, 01:03 PM  #2 
Senior Member Joined: Sep 2015 From: USA Posts: 1,755 Thanks: 899 
a+

October 24th, 2017, 10:40 PM  #3 
Newbie Joined: Oct 2017 From: Hanoi Posts: 4 Thanks: 1 
Woo hoo!


Tags 
board, chess, choosing, probability, shape 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Permutation combination(Rectangles on chess board)  jayeshtrivedi  Algebra  2  October 9th, 2014 09:27 AM 
the chess board  Fetigue  New Users  5  May 1st, 2014 11:02 AM 
Probability : choosing balls (need help)  rnck  Advanced Statistics  5  July 2nd, 2013 03:41 PM 
chess board problem  meph1st0pheles  Advanced Statistics  3  February 3rd, 2010 09:31 AM 
Probability of winning a chess tournament  Natalya  Algebra  1  November 15th, 2007 05:52 AM 