What proportion of all americans believe the president is doing a good job? a recent poll found that 39% of 1000 randomly selected americans approved of the way george w. bush is handling his job as president. a. does this mean that only 39% of all americans approve of the way george w. bush is handling his job as president? b. for a sample proportion, as long as the population is greater than ten times the sample size, we can approximate the standard deviation to be what is the standard deviation for this sample? c. what is the critical value for a 90% confidence interval? d. what is the critical value for a 95% confidence interval? e. what is the 90% confidence interval? be sure to include the formula with your numbers plugged in. use the model: f) what is the 95% confidence interval?