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5. A professor teaching introductory psychology gave the grades that follow. According to the normal curve, she should have given about 4% A’s, 14% B’s, 64% C’s, 14% D’s, and 4% F’s. Do a Chi-Square to determine if the actual grade assignment significantly departed from the normal distribution. α=.05

A’s B’s C’s D’s F’s
25 35 60 30 20

• statistics -

X^2 = ∑ (O-E)^2/E, where O = observed frequency and E = expected frequency.

∑ = sum of all the cells.

E = (column total * row total)/grand total

df = n - 1, where n = number of cells

Look up value in X^2 table in the back of your textbook.

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