Suppose that a single y observation is made at each of the x values 5, 10, 15, 20, and 25.
a. If s = 4, what is the standard deviation of the statistic b?
b. Now suppose that a second observation is made at every x value listed in Part (a) (for a total of 10 observations). Is the resulting value of σb half of what it was in Part (a)?
c. How many observations at each x value in Part (a) are required to yield a σb value that is half the value calculated in Part (a)? Verify your conjecture.