Question

Johnsons new plant makes pistons where the variation in radius must be minimal. You sample 24 pistons and find a standard deviation of 1.63mm. Asuming the radii to be normally distrubet find a. x2l and x 2r for a confidence.     and.    b. x2l and xr for a 95 confidence.   and.     c. The 98% confidence for the population std dev.  

Answer 1

df = n-1 = 24-1 = 23

s = 1.63

95% Confidence Intervals

               CI for        CI for
Method          StDev       Variance
Chi-Square (1.27, 2.29) (1.60, 5.23)

98% Confidence Intervals

               CI for        CI for
Method          StDev       Variance
Chi-Square (1.21, 2.45) (1.47, 5.99)