Question 763481
Using the formula for Confidence Interval for a Proportion P-hat +/- z_a/2*sqrt((p-hat*q-hat)/n)=> 0.53 +/- (1.96*sqrt((0.53*0.47)/400) => 0.53 +/- (0.0489) => (0.4811,0.5789)  
           Lower and upper limits to 3 decimal places is 0.481 and 0.589.

Hope that helps.

Ed