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W14_ExSol

# W14_ExSol - (d R = p R 2 = 89 5(e H& 1 = 0 H a& 1 6 =...

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1. n = 10 ; ° x = 7 ; s x = 3 : 97 ; ° y = 108 ; s y = 16 : 47 ; r = 0 : 9646 (a) S xx = 142 ; S xy = 568 ; S yy = 2442 : ^ ° 1 = S xy S xx = 4 ; ^ ° 0 = ° y ° ^ ° 1 ° x = 80 Regression equation: y = 80 + 4 x (b) 2* ^ ° 1 = 8 : John°s annual sales is \$8,000 higher than Sarah. (c) It is not appropriate, since x = 20 is far away from the range of the data, from which regression line was developed. (d) H 0 : ° 1 = 0 H a : ° 1 > 0 t = ^ ° 1 s= p S xx = 10 : 34 > t 8 ; 0 : 05 = 1 : 8595 : Reject H 0 : At 5% level of signi±cance, there is a positive linear relationship between x and y: (e) ^ y = 80 + 4 ± 9 = 116 : (f) s = 4 : 61 ; C.I.: ^ y ² t 8 ; 0 : 025 s q 1 n + (9 ° ° x ) 2 S xx ; or 116 ² 3 : 81 (g) P.I.: ^ y ² t 8 ; 0 : 025 s q 1 + 1 n + (9 ° ° x ) 2 S xx ; or 116 ² 11 : 29 2. (a) n = 9 (b) s 2 = SSE= 7 = 1485 : 26 (c) R 2 = SSR=SST
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Unformatted text preview: (d) R = p R 2 = 89 : 5% (e) H : & 1 = 0 H a : & 1 6 = 0 t = 5 : 29 > 2 : 3646 = t 7 ; : 025 : Reject H : at 0.05 level of signi±cance, X is useful in predicting Y: (f) x = 50 ; ^ y = 20 + 7 : 21 ± 50 = 380 : 5 (g) 95% C.I: ^ y ² t 7 ; : 025 s q 1 n + (50 & & x ) 2 Sxx where s = p 1485 : 26 = 38 : 54 In addition, ^ ± ^ & 1 = s= p S xx = 1 : 3626 ; = ) S xx = 799 : 95 : Finally, 95% C.I.: 279.18, 481.82 1...
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