Question

Suzy wants to assess the accuracy of a laboratory scale, and a standard weight is known to weigh 20 grams is repeatedly weighed. The scale readings are normally distributed with an unknown mean µ. Suppose you weigh the weight 9 times and obtain a mean weight of 20.005 grams and a standard deviation s = 0.003. Is this data strong evidence of bias in the scale?
Ho: u=20
Ha u does not equal 20

What are the appropriate degrees of freedom for this test?

8

9

10

20

64

Answer 1

@tkhunny

Answer 2

@whpalmer4

Answer 3

@e.mccormick

Answer 4

Well, it's not greater than 9.