Answer
The distribution must be normal.
$μ_{x̄} = 64$
$σ_{x̄} = 3.80$
Work Step by Step
In order to use the normal model to compute probabilities involving the sample mean, the distribution must be normal. Sampling distribution of x̄ is given as:
$μ_{x̄} = μ = 64$
$σ_{x̄} = σ/\sqrt n = 17/\sqrt 20 = 3.80$
