Answer
Reject $H_{o}$ at α = 0.05
Work Step by Step
$z = \frac{x̄ - μ}{σ/\sqrt n}$
$z = \frac{39.2-40}{1.97/\sqrt 5}$
$ = \frac{-0.8}{0.394}$
= -2.03
P(z < -2.03 or z > 2.03) = 0.0424 < α
Hence reject $H_{o}$ at α = 0.05
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