In Exercise 13.17, we considered a regression of y= oxygen consumption on x = time spent...

In Exercise 13.17, we considered a regression of y= oxygen consumption on x = time spent exercising. Summary quantities given there yield

a. Calculate s_a+b(2.0), the estimated standard deviation of the statistic a + b(2.0).

b. Without any further calculation, what is s_a+b(3.0) and what reasoning did you use to obtain it?

c. Calculate the estimated standard deviation of the statistic a + b(2.8).

d. For what value x* is the estimated standard deviation of a + bx* smallest, and why?