For any sizeable data set, and even for the small ones, you'll definitely want to use Minitab to calculate the confidence and/or prediction intervals for you. To do so:

1. Under the Stat menu, select Stat, and then select Regression:

   

2. In the pop-up window that appears, in the box labeled Response, specify the response and, in the box labeled Predictors, specify the predictor variable:

   

   Then, click on the Options... button.

3. In the pop-up window that appears, in the box labeled Prediction intervals for new observations, type the value of the predictor variable for which you'd like a confidence interval and/or prediction interval:

   

   In the box labeled Confidence level, type your desired confidence level. (The default is 95.) Then, select OK.

4. And, select OK on the main pop-up window. The output should appear in the session window. The first part of the output should look something like this:

   The regression equation is NEXT = 33.8 + 10.7 DURATION

   Predictor	Coef	SE Coef	T	P
   Constant	33.828	2.262	14.96	0.000
   DURATION	10.7410	0.6263	17.15	0.000

   Analysis of Variance

   Source	DF	SS	MS	F	P
   Regression	1	13133	13133	294.08	0.000
   Residual Error	105	4689	45	0.000
   Total	106	17822

   while the second part of the output, which contains the requested intervals, should look something like this:

   Predicted Values for New Observations

   New Obs	Fit	SE Fit	95% CI	95 % PI
   1	85.385	1.059	(83.286, 87.484)	(71.969, 98.801)

   Values of Predictors for New Observations

   New Obs	DURATION
   1	4.80