problem-7.5

problem-7.5  The prop.test function gives
> n = 100; phat = 0.45
> prop.test(n*phat, n, conf.level = 0.8)
...
80 percent confidence interval:
 0.3827 0.5190
...
> prop.test(n*phat, n, conf.level = 0.9)
...
90 percent confidence interval:
 0.3658 0.5370
...