17.1 (i) For a binary response y, let y be the proportion of ones in the sample (which is equal to the sample average of the y;). Let a be the percent correctly predicted for the outcome y = 0 and let be the percent correctly predicted for the out- come y = 1. If p is the overall percent correctly predicted, show that p is a weighted average of and : = (1-y) o + y. (ii) In a sample of 300, suppose that y = .70, with y, = 1 and 90 with y; = 0. Suppose that the percent correctly pre- dicted when y = 0 is 80, and the percent correctly predicted when y = 1 SD ON LE is 40. Find the overall percent correctly predicted.