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In each of the following studies a single sample's mean is being compared to a population with a known mean and an unknown variance. For each study decide whether the result is significant. Signific.
Sample Size Population Mean Estimated Pop. Variance Sample Mean Tails Level
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A (N) (S 2nd power) (M)

(a) 64 12.40 9.00 11.00 1 (low .05
predicted)
(b) 49 1,006.35 317.91 1,009.72 2 (high .01
predicted)
(c) 400 52.00 7.02 .01