In the manufacture of machinery, it is essential to utlize parts that conform to

Question

   In the manufacture of machinery, it is essential to utlize parts that conform to specifications. In the past, diameters of the ball bearings produced by a certain manufacturer had a variance of .00156. To cut costs, the manufacturer instituted a less expensive production method. The variance of the diameters of 100 randomly sampled bearings produced by the new process was .00211. Do the data provide sufficient evidence to indicate that the diameters of ball bearings produced by the new process are more variable than those produced by the old process? Test at = .05

Explanation / Answer

Given ^2=0.00156, n=100, s^2=0.00211 The test hypothesis is Ho:^20.00156 The test statistic is X^2=(n-1)*s^2/^2 = (100-1)*0.00211/0.00156 = 133.9 X^2(with df=n-1=99) = 123.22 (check chisqare table) Since 133.9>123.22, we reject Ho.

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