text: artofspeed 3 years ago hard probability question.. help plz?
  
  1. artofspeed
  
  2. artofspeed
  
  I dunno :S
  
  3. kevinkeegan
  
  \[4^{4} = 256\]
  
  4. kevinkeegan
  
  want me to explain?
  
  5. shivam_bhalla
  
  6. kevinkeegan
  
  okay you have 4 choices tiles to use WWW WWB WBWetc... each will take up 3 slots and you have 10 slots only so we use 3 diff groups( groups as in WWW= 1grp, WBW=1grp an so on) first, taking up 9 slots, so the probability of arranging the 3 grps = 4X4X4 ; now we left with 1 last slot for the single white tile; and we can put the white tiles @ 4 different places( trying drawing out): so that gives us extra 4 different combos and therefore, total probability= 4X4X4X4
  
  7. kevinkeegan
  
  |dw:1335113090901:dw| arrow point to last slot for single white tile
  
  8. ParthKohli
  
  I know the answer. http://ptri1.tripod.com/ptreal1r.gif See this picture of a pascal's triangle. Now see the row 2 and sum all the numbers of row 2 You get 4! See the row 10 and get the sum of all the numbers in row 10. You get the answer!
  
  9. kevinkeegan
  
  one thing to note: question did not state if the tiles can be reused, if cannot reuse, answer is 4X3X2X4
  
  10. ParthKohli
  
  11. artofspeed
  
  12. kevinkeegan
  
  pascal triangle does not work here becasue the tiles are in groups of 3
  
  13. ParthKohli
  
  14. kevinkeegan
  
  15. ParthKohli
  
  The final line, see it.
  
  16. kevinkeegan
  
  is they want us to use the 4 combo of WWW WWB WBW BWW then im right
  
  17. kevinkeegan
  
  if*
  
  18. shivam_bhalla
  
  Somebody please explain the question. It is confusing
  
  19. kevinkeegan
  
  they want u to use the combos to fill up the 10 slots
  
  20. ParthKohli
  
  They're asking us the different colour patterns in a ten by one rectangle. There are 1024 such patterns. Try it on your own.
  
  21. ParthKohli
  
  They're asking us about the number of patterns possible in this case.
  
  22. kevinkeegan
  
  last line : "using THESE TILES " and i suppose THESE TILES refer to the 4 different colour patterns
  
  23. kevinkeegan
  
  the tiles are not individual they come in sets
  
  24. ParthKohli
  
  All right. You're right, I'm wrong. Okay?
  
  25. kevinkeegan
  
  |dw:1335113911913:dw|
  
  26. artofspeed
  
  @kevinkeegan, 'these tiles' actually refer to the 3 tiles in the picture
  
  27. kevinkeegan
  
  yep and the 3 tiles form the 4 colour patterns they giv WWW WBW BWW WWB
  
  28. PaxPolaris
  29. niki
  
  hey i think the ans is 385 plz check