Since sample size is > 40, we use the z-score
in calculating for the confidence interval.
The formula is given as:
Confidence Interval = X ± z * σ / sqrt (n)
Where,
X = mean = $50,340
z = z-score which is taken from standard distribution
tables at 90% confidence interval = 1.645
σ
= standard deviation = $10,780
n = sample size = 45
Substituting to the equation:
Confidence Interval = 50,340 ± 1.645 * 10,780 / sqrt (45)
Confidence Interval = 50,340 ± 1,607
Confidence Interval = $48,733 to $51,947
<span>Therefore the salary range of the personnel is $48,733 to $51,947.</span>
