October 8th, 2010 
Admin Question by Mshmsha Gwad: please answer….the problem…?
the indiana state tax board has determined that the usual variance in property-tax assessment for “type A” houses is 1,000,000 (dollars squared). a random sample of 20 houses in vermillion county indicated avariance of 600,000. is this an unusually low variance, assuming a normal distribution of assessments?
Best answer:
Answer by falzoon
I think this requires the F-test. My memory and knowledge
on this are not too crash-hot, but here goes -
F = variance1 / variance2
= 1,000,000 / 600,000
= 1.67
I think the number of degrees of freedom of both numerator
and denominator is DF = 20 – 1 = 19.
Looking up the table for the F-distribution (1-tailed test),
gives a value of 2.16 at the 95% confidence limit.
Because 1.67 < 2.16, we can say with 95% confidence that
there is no difference between the values.
I hope that's right, but I'm prepared to be shot down in flames!
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