The regression equation is ŷ = 67.79 + 6.72x. How many participants are needed in order for the school to raise $800?

Set the predicted amount to $800: 800 = 67.79 + 6.72x. Subtract 67.79 and divide by 6.72 to get x ≈ 108.96 participants. Since the school needs a whole number of participants, it needs 109, which is choice C.

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