Answer: The margin of error for a 95% confidence interval around this sample mean is 1.412.
Explanation:
We know that the formula to find the margin of error is given by :-
, where
= population standard deviation
n= sample size , z* = critical z-value as per confidence level.
As per given , we have
=4.2
n= 34
By z-table , for 95% confidence level : z* = 1.96
Then, the margin of error will be :

Hence, the margin of error for a 95% confidence interval around this sample mean is 1.412.