Finding a Prediction Interval. In Exercises 21–24, refer to the Table 10-1 sample data.

Let x represent the duration time (in seconds) and let y represent the time interval (in minutes) after the eruption to the next eruption. Use the given duration time and the given confidence level to construct a prediction interval estimate of the time interval after the eruption to the next eruption. (See the example in this section.)

21. x
180 sec; 99% confidence 22. x
180 sec; 90% confidence 23. x
200 sec; 95% confidence 24. x
120 sec; 99% confidence 10-4 BEYOND THE BASICS 25. Confidence Intervals for b0 and b1 Confidence intervals for the y-intercept b0 and slope b1 for a regression line can be found by evaluating the limits in the intervals below.

where E 5 ta>2 se

ã

1 n

1 x2 Sx2 2 sSxd2 n

b0 2 E , b0 , b0 1 E sy 5 b0 1 b1xd 10-4 Variation and Prediction Intervals 565 continued 566 Chapter 10 Correlation and Regression where In these expressions, the y-intercept b0 and the slope b1 are found from the sample data and is found from Table A-3 by using n  2 degrees of freedom. Using the duration interval after eruption times in Table 10-1, find the 95% confidence interval estimates of b0 and b1.