95% confidence interval would be (58.96, 69.04).
Explanation:
Since we have given that
Number of dogs' weight = 20
Mean = 64 ounces
Standard deviation = 11.5 ounces
We need to find the 95% confidence interval.
So, z = 1.96
so, interval would be

Hence, 95% confidence interval would be (58.96, 69.04).