8. Over many years of teaching an introductory statistics class, it is calculate

Question

8. Over many years of teaching an introductory statistics class, it is calculated that the overall average on the final exam is 64%, with scores normally distributed with a standard deviation of 8. In a particular term, the professor calculates his class average to be 61% He would like to use his class of 40 students as a sample to test if there is reason to believe statistics students across all sections of the course are below the historic average. At which of the following levels of significance should the appropriate null hypothesis be rejected? (i)a-.1, (ii) = .05, (iii)a-01 (A) None (B) Only (i) (C) Only (i) (D) Only (ii)

Explanation / Answer

TS = (xbar - mu)/(Sd/sqrt(n)

= ( 61 - 64)/(8/sqrt(40))= -2.37170

p-value = P(Z < -2.37170)

= 0.0088

if p-value < alpha

we reject the null

hence H) All is correct

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