Answer:
confidence interval = (27.9, 28.3)
Step-by-step explanation:
Here we are given the population std deviation value as 5.7. So we can use Z critical value for finding out confidence interval.
Sample size n = 4386
Std error of sample mean =
Sample mean = 28.1
Z critical value two tailed for 98% = 2.326
margin of error = ±2.326*0.0861 =0.2003
confidence interval lower bound
=
Upper bound
=
After rounding off we get
confidence interval = (27.9, 28.3)