Answer:
99% Confidence interval: (50.9,61.3)
Step-by-step explanation:
We are given the following in the question:
Sample mean, [tex]\bar{x}[/tex] = 56.1
Sample size, n = 72
Alpha, α = 0.01
Sample standard deviation, σ = 16.7
Degree of freedom = n - 1 = 71
99% Confidence interval:
[tex]\bar{x} \pm t_{critical}\displaystyle\frac{s}{\sqrt{n}}[/tex]
Putting the values, we get,
[tex]t_{critical}\text{ at degree of freedom 71 and}~\alpha_{0.01} = \pm 2.64[/tex]
[tex]56.1 \pm 2.64(\dfrac{16.7}{\sqrt{72}} ) \\\\= 56.1 \pm 5.19\\\\ = (50.91 ,61.29)\approx (50.9,61.3)[/tex]