Z = (score-mean)/SEm
SEm = SD/√n
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.
The Toylot company makes an electric train with a motor that it claims will draw an average of only 0.8 ampere (A) under a normal load. A sample of twelve motors was tested, and it was found that the mean current was x = 1.26 A, with a sample standard deviation of s = 0.40 A. Do the data indicate that the Toylot claim of 0.8 A is too low? (Use a 1% level of significance.
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