Answer:
a) 7.4
b) 54.2 to 61.6
Step-by-step explanation:
Margin error = 3.7
a) Length of the confidence interval = 2*margin error
= 2*3.7
= 7.4
b) Sample mean = 57.9
Confidence interval = Sample mean +/- margin error
= 57.9+/-3.7
= 57.9 - 3.7 to 57.9+3.7
= 54.2 to 61.6