Answer:
(30.09, 32.91)
Step-by-step explanation:
Mean number of pounds of trash = x = 31.5 pounds
Standard deviation = s = 7.8 pounds
Sample size = n = 120
Confidence level = 95%
Since, we are given the sample standard deviation instead of the population standard deviation, we will use t-test to find the confidence interval.
Degrees of freedom = df = n - 1 = 120 - 1 = 119
The t-value associated with 95% confidence interval and df=119 from the t-table comes out to be:
t = 1.98
The formula to calculate the confidence interval is:
Using the values in above expression we get:
Thus, the 95% confidence interval for the mean number of lbs of trash per person per week that is generated in the city is (30.09, 32.91)