Answer: 10.09 or 15.03
explanation:
Formula for confidence interval(CI) is CI = x ± z * (sd/ Sqrt(n))
Where x is mean = 12.56
z is value for normal distribution 99% confidence =2.58
sd is standard deviation=3.03
Sqrt is square root
n is sample population = 10
CI =12.56±2.58*(3.03/sqrt(10)
=12.56±2.47
=15.03 or 10.09
With 99% confidence, the average number of commercial minutes is between 10.09 and 15.03 minutes, based on sample data.
