Answer: The estimated margin of error = 0.5 centimeter
The sample mean = 4.3 centimeters
Explanation:
The confidence interval for population mean is given by :-

or

, where
= sample mean.
E = Margin of error .
The given confidence interval : (3.8,4.8 )
Lower limit :
(1)
Upper limit =
(2)
Eliminate equation (1) from (2) , we get

⇒ The estimated margin of error = 0.5 centimeter
Add (1) and (2) ,we get
⇒ The sample mean = 4.3 centimeters