bonanova Posted October 14, 2008 Report Share Posted October 14, 2008 You purchase a card on which there is a number of scratch-off squares. One square is marked LOSER; two other squares have identical symbols. If both symbols appear before the loser square appears, you win a prize. The odds against winning are 2:1 against. How many squares are there on the card? Quote Link to comment Share on other sites More sharing options...
0 andromeda Posted October 14, 2008 Report Share Posted October 14, 2008 Maybe 6 = 4 loser + 2 winning Quote Link to comment Share on other sites More sharing options...
0 bonanova Posted October 14, 2008 Author Report Share Posted October 14, 2008 Maybe 6 = 4 loser + 2 winning Re-read line two of the OP. Quote Link to comment Share on other sites More sharing options...
0 Guest Posted October 14, 2008 Report Share Posted October 14, 2008 Three??? Quote Link to comment Share on other sites More sharing options...
0 Guest Posted October 14, 2008 Report Share Posted October 14, 2008 the total number of squares is irrelevant. The squares actually affecting the game are set. Since any other squares would have no effect you can treat the game as if only the relevant three exist and the odds will always be 2:1 against. Quote Link to comment Share on other sites More sharing options...
0 dms172 Posted October 14, 2008 Report Share Posted October 14, 2008 (edited) five-3 chances to win six changes to lose Edited October 14, 2008 by dms172 Quote Link to comment Share on other sites More sharing options...
0 Prime Posted October 14, 2008 Report Share Posted October 14, 2008 Against...against? Double negative? Does it mean the probability of winning is 1/3? There must be at least 3 scratch boxes to accomodate the conditions. The probability of win appears to be the same 1/3 regardless of number of scratch boxes. See it this way: When scratching out boxes, we disregard all except those three that count. There are only three possibilities for the order in which those 3 can be arranged: LSS, SLS, SSL. The three combinations are equally likely regardless of how many irrelevant boxes you scratched out before, or in between. Quote Link to comment Share on other sites More sharing options...
Question
bonanova
You purchase a card on which there is a number of scratch-off squares.
One square is marked LOSER; two other squares have identical symbols.
If both symbols appear before the loser square appears, you win a prize.
The odds against winning are 2:1 against.
How many squares are there on the card?
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