Answer: ($3.532, $4.166)
Step-by-step explanation:
Given : Significance level : 
Critical value : 
Sample size : n= 157
Sample mean : 
Standard deviation : 
The confidence interval for population mean is given by :_


Hence, the 0% confidence interval for the average tip given at this restaurant = ($3.532, $4.166)
I basically pick a couple random numbers for both variables and plug them in to see if they are true.
A = 1/2 h(b + x)
2a = h(b + x)
2a/h = b + x
x = 2a/h - b