Question

Boxes of cereal are labeled as containing 14 ounces. Find the 95% confidence interval for population variance of the weight in boxes if a sample of 12 boxes has a standard deviation of .06 oz.   

(please show work of calculation)

Answer 1

PAGE NO DATE: 14 > n = 12 sid= 0.06 &² 8 Sample UCCEEEEEEE -0.0036 veriance - We want 95% Confindence Variance (0) which is interval for Population given by, (mb s² L o2 s (m) 42 cutere catical values are m= degree of Redono I samble size Nowgi These values can x = 1-0.95= 0.05 be calculated from degree of freedon = 12 Chisquare table X = (221-0.05 , 12-1) = 210.915, 11) = 3.8157 x = (X 105, 12-1) = x2025, 1) =21:42 Substituting above values informula. ((12-1) (0.00362 (124) (0.0036) 21.92 - 3.8157 < 22

4 2 3 11x00036 21.92 1 X 0.0036 3.8157 s 02 < 10.039.6 21.92 0.0396 3.8157 I o .0018 262 2:0.0104 Hence, 95% CI for Pop Variance is given by (0.0018 / 22 20:0104).