409Hw04ans - STAT 409 Fall 2005 Homework #4 (due Friday,...

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STAT 409 Fall 2005 Homework #4 (due Friday, September 25, by 4:00 p.m.) From the textbook: 6.4-8 a) x = 46.42 ; b) s 2 = 41.682, s 6.456, t 0.05 ( 4 ) = 2.132, 5 456 . 6 132 . 2 42 . 46 ± or 46.42 ± 6.156 or ( 40.264, 52.576 ) . 6.4-10 t 0.10 ( 27 ) = 1.314, ( 29 ( 29 , 28 31 . 0 314 . 1 45 . 21 - = ( 29 21.373, . 6.4-12 a) x = 3.580 ; b) s 0.512 , c) t 0.05 ( 9 ) = 1.833, ( 29 10 512 . 0 833 . 1 580 . 3 , 0 ± = ( 0, 3.877 ) .
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6.4-18 n = 1219 – large, use z 0.005 to approximate t 0.005 ( 1218 ). z 0.005 = 2.576, ( 29 1219 02 . 0 576 . 2 05 . 6 ± or 6.05 ± 0.0015 or ( 6.0485, 6.0515 ) . 6.8-2 n = ( 29 ( 29 ( 29 2 2 5 . 1 169 96 . 1 = 288.547 so the sample size needed is 289 . 6.8-4 n = ( 29 ( 29 ( 29 2 2 5 . 0 9 . 34 96 . 1 = 536.28736 so the sample size needed is 537 . Then use 537 2 New New s z x α ± = 537 96 . 1 New New s x ± . OR t 0.025 ( 28 ) = 2.048; n = ( 29 ( 29 ( 29 2 2 5 . 0 9 . 34 048 . 2 = 585.5248384 so the sample size needed is 586 . Then use ( 29 586 28 2 Old New s t x ± = 586 9 . 34 048 . 2 ± New x .
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6.8-6 n = ( 29 ( 29 ( 29 2 2 2 5 7 . 33 96 . 1 = 174.51466816 so the sample size needed is 175 . 6.5-2 “Hint”: Equal variances x ( x x - ) 2 y ( y y - ) 2 644 493 532 462 565 10983.04 2134.44 51.84 5959.84 665.64 623 472 492 661 540 502 549 518 6142.640625 5274.390625 2769.390625 13543.140625 21.390625 1816.890625 19.140625 708.890625 Total: 2696 19794.80 4357 30295.875000 x = 5 2696 = 539.2, s x 2 = 4 8 . 19794 = 4948.7, y = 8 4357 = 544.625, s y 2 = 7 875 . 30295 4327.982. ( 29 ( 29 2 8 5 982 . 4327 1 8 7 . 4948 1 5 2 pooled - + - + - = s 4553.7, pooled s 67.481. t 0.05 ( 11 ) = 1.796, ( 29 8 1 5 1 481 . 67 796 . 1 625 . 544 2 . 539 + ± - 5.425 ± 69.092 or ( 74.517, 63.667 ) .
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6.5-4 x ( x x - ) 2 y ( y y - ) 2 1612 1352 1456 1222 1560 1456 1924 10057.2245 25508.6531
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This note was uploaded on 10/12/2011 for the course STATISTICS stat 410 taught by Professor Stepanov during the Spring '11 term at University of Illinois, Urbana Champaign.

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409Hw04ans - STAT 409 Fall 2005 Homework #4 (due Friday,...

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