Answer:
545 randomly selected air passengers must be surveyed.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of , we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
The margin of error is:
95% confidence level
So , z is the value of Z that has a pvalue of , so .
Assume that you want to be 95% confident that the sample percentage is within 4.2 percentage points of the true population percentage.
We dont know the true proportion, so we use , which is when the largest sample size will be needed. We have to find n for which . So
Rouding up
545 randomly selected air passengers must be surveyed.