The reasoning of tests of significance

A one-sample t test of the null hypothesis that the average performance on this quiz is what you would expect if they were randomly guessing (a mean of 6.5) is significant. The number of items correctly answered (M = 5.28, SD = 1.18) was significantly less than what would be expected were they randomly guessing, t(17) = 4.40, p < .001, g = 1.04. A 95% confidence interval for the mean runs from ... ................
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