A new television series must prove that it has more than 25% of the viewing audience after its initial 13-week run in order to be judged successful. Assume that in a sample of 400 households, 112 were...

 A new television series must prove that it has more than 25% of the viewing audience after its initial 13-week run in order to be judged successful.  Assume that in a sample of 400 households, 112 were watching the series.

(a) Find the value of Z_a/2
in order to find a
99% confidence interval for theproportion of the viewing audience after its initial 13-week run.