8. (3 points) A factory manufactures steel ball bearings with a diameter precision (stan- dard deviation) of 50 m. What would be the probability that the sample standard devi- ation is greater than 53 m for a sample of 20 balls? O 0.0968 0.4347 0.2673 O 0.1208 0.2223 0.0769 O 0.1494 0.3739 0.3179 0.1831 9. Consider the following sample of measurements: 12.6 13.6 14.1 12.3 13.6 13.4 14.2 (a) (2 points) Compute the sample mean x. 12.9 13.2 13.5 13.4 12.8 13.8 13.7 13.9 (b) (3 points (bonus)) Compute the sample variation s. O 0.41 O 0.31 0.81 0.61 0.21 0.71 0.51 0.11 (c) (3 points) Let the null hypothesis be Ho: = 14 (and hence the alternative hypoth- esis is H: 15.2021 > 14.9858 > 15.3149 > 15.1032