PP-exam1

PP-exam1 - 5. Given a regular deck of 52 cards, how many 13...

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STOR 215, Fall 2007 Practice Problems for Midterm I: Questions in Old Exams 1. (a) How many arrangements are there of the letters in the word SHENANI- GAN? (the ’A’ letters are considered indistinguishable from each other, and the ’N’ are indistinguishable from each other) (5 points) (b) How many of these are such that there are no ’N’ letters next to each other? (5 points) 2. Let k and n be integers, 1 k n . Prove combinatorially ± n k ² = ± n - 1 k ² + ± n - 1 k - 1 ² . (5 points) 3. Draw Pascal’s triangle down to row 5. Mark the location of ± 5 1 ² and ± 4 3 ² in it. (5 points) 4. We know that n ( n + 1 )( 2 n + 1 ) 6 + ( n + 1 ) 2 = ( n + 1 )( n + 2 )( 2 n + 3 ) 6 (so you do NOT need to prove this, you can use it without proof). Prove that for all positive integers n , n i = 1 i 2 = n ( n + 1 )( 2 n + 1 ) 6 (7 points)
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Unformatted text preview: 5. Given a regular deck of 52 cards, how many 13 card hands are there, which have 3 pairs AND 3 other cards of the same rank (but different from the rank of the pairs), AND 4 remaining cards of the same rank (but different from the rank of the pairs, and the triplet)? Say 2D, 2H; 4S, 4C; 6S, 6H; AC, AH, AS; QH, QS, QC, QD is such a hand. (10 points) 6. You are given a deck of 60 cards, which has 10 ranks (from 1 through 10), and 6 suits, called red, blue, white, black, green and yellow. How many 4 card hands are there, in which all the suits and all the ranks are different? Say 2 yellow, 4 green, 5 white, 9 black is such a hand. (12 points) 1...
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This note was uploaded on 03/20/2008 for the course STOR 215 taught by Professor Lu during the Fall '07 term at UNC.

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