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Brittany

Mr. Shaddick
im studying for the test i have to write tomorrow. and i was just wondering how to do p.261 #4 b&c. i got a by doing 1*6*5*4=840.
Also, page 299 #12.. no clue...give me a hint.
__________________________
Mr. Shaddick: For 4b, you have to consider that there are 4 options for the last digit (the odd number). Then, you'll have 6 options for digit one, 5 for digit two, and 4 for digit three. So, it would be 4*6*5*4. For even numbers, there are 3 options for the last digit. As for #12a uses combinations while #12b uses permutations. You know that all 8 of the windows have to be occupied, which means that 2 of the aisle seats will be occupied. There are 8C8 ways (=1) to fill the window seats and 12C2 combinations for filling the aisle seats. So the answer is 8C8 times 12C2. For part b, come in at lunch - it will be difficult to explain here (and I have to head off to practice). I hope that the tournament went well today! Here's my shot at part b) .... you have to fill the aisle seats, so you have to consider all of the ways to do that (10P8) and then multiply that by the number of ways the remaining two passengers can be arranged among the 12 aisle seats. The second-last passenger has 12 possible seats and the last passenger has 11 possible seats to choose from. In total, the answer will be 10P8 * 12 * 11.

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