Answer
Reject $H_{o}$ at α = 0.02
Work Step by Step
$z = \frac{x̄ - μ}{σ/\sqrt n}$
$z = \frac{8420-8550}{314/\sqrt 38}$
= -2.55
P(z < -2.55 or z > 2.55) = 0.0108 < α
Hence reject $H_{o}$ at α = 0.02
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