Answer: A 95% lower confidence bound for the mean capacity of this type of battery = 175.85
Explanation:
Given: The capacities were measured for a sample : n= 120 batteries.
and

lower confidence bound=

Critical z value for 9%% confidence = 1.96
So, a 95% lower confidence bound for the mean capacity of this type of battery will be :

Hence, a 95% lower confidence bound for the mean capacity of this type of battery = 175.85