Diones favorite excercise machine is a stair climber. On the “random” setting, it changes speeds at regular intervals so that total number of simulated “floors” she climbs varies from session to session. Dione also exercises for different lengths of time each session. She decides to explore the relationship between how long she works out on the stair climber (in minutes) and the number of floors it tells her that she has climbed. Dione records minutes of climbing time and number of floors climbed for six exercise sessions. Computer output and a residual plot from a linear regression analysis of the data are shown below.

Predictor Coef SE Coef T P Constant -3.822 5.458 -0.70 0.522 Workout time 5.2150 0.2779 18.76 0.000 (min)
S = 2.3472 R-Sq = 98.9% R-Sq(adj) = 98.6%



* (a)  Identify and interpret the slope and y-intercept of the regression line. If the y-intercept does not have meaning in this context explain why not. 




* (b)  Is the line an appropriate model for these data? Justify your answer. 




* (c)  Interpret the value of s from the computer output. 




* (d)  Interpret the value of r2 from the computer output.