On Tue, 29 Jul 2003 21:16:09 +0800, James Lo <[EMAIL PROTECTED]> wrote:
>Suppose that four cards are drawn successively from an ordinary deck >of 52 cards, with replacement and at random. What is the probability >of drawing at least one king? > >Answer from the book: 0.274 > >My solution and answer: > >Let AC = be the sample points where King is not found >AC = 51*51*51*51 or 51^4 = 6765201 > >Let A = be the total number of sample points > >A = 52*52*52*52 or 52^4 = 7311616 > >Pr(drawing at least one king) = 1 - Pr(drawing no king) = 1 - >(51^4/52^4) = 1 - 0.9253 = 0.0747 > > >Anyone can clarify? If my answer is correct, then the answer shown on >the textbook could be a typo error. Otherwise, which part is my error. > > >Thanks. > > >James > Thanks for all your explanations. I know what's the problem and where's my mistake. The correct interpretation of 'drawing at least one king' is 'drawing a king at least once'. So the correct solution is: 1 - Pr(No at least one king) = Pr(with at least one king) 1 - (48/52)^2 = 1 - 0.7260 = 0.274 . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
