In order to be effective, reflective highway signs must be picked up by the automobile's headlights. To do so at long distances requires that the beams be on "high". A study conducted by highway engineers reveals that 45 of 50 randomly selected cars in a high-traffic- volume area have the headlights on low beam.
(a) Find a point estimate for p, the proportion of automobiles in this type area that use low beams.
(b) Find a 90% confidence interval on p.
(c) Test
Ho : p = .95 vs H1 : p < .95 at the significance level of 0.05
(d) How large a sample is required to estimate p within .02 with 95% confidence?