Answer:
The mean is of 33.6
The margin of error is of 5.2.
Explanation:
Confidence interval concepts:
A confidence interval has two bounds, a lower bound and an upper bound.
A confidence interval is symmetric, which means that the point estimate used is the mid point between these two bounds, that is, the mean of the two bounds.
In this question:
Lower bound: 28.4
Upper bound: 38.8
Mean
(28.4+38.8)/2 = 33.6.
The mean is of 33.6
Margin of error:
(38.8 - 28.4)/2 = 5.2
The margin of error is of 5.2.