Answer
$\mu\gt1.95$ or $\mu\lt2.40$
$\mu\gt1.95$ means that at a 95% confidence, the mean revenue is greater than 1.95 dollars.
$\mu\lt2.40$ means that at a 95% confidence, the mean revenue is less than 2.40 dollars.
Work Step by Step
1. From the data set, we get $\bar X=2.175, s=0.5847 , n=20 $
2. At a 95% confidence and $df=19$, the critical t-value is $t_{\alpha}=1.729 $ (use table F)
3. The error defined in this problem can be found as $t_{\alpha}\times\frac{s}{\sqrt n}=1.729\times\frac{0.5847}{\sqrt {20}}=0.226$
4. Thus, the one-sided confidence interval can be found as $\mu\gt1.95$ or $\mu\lt2.40$
5. $\mu\gt1.95$ means that at a 95% confidence, the mean revenue is greater than 1.95 dollars.
6. $\mu\lt2.40$ means that at a 95% confidence, the mean revenue is less than 2.40 dollars.
