Answer:
Step-by-step explanation:
Given that X, the number of square feet per house is N(mean, 137)
Sample size = 19
Sample mean x bar =1350 sq ft
Since population std dev is given,
std error of sample =
Since sample size is small, t critical value can be used
df = 18
t value for 80% two tailed = 1.333
Margin of error = ±1.333(std error) = ±
Confidence interval = sample mean ±margin of error
=