A confidence interval estimate for a single proportion, based on a random sample of 500 is 0.372 to 0.428. From this information, what level of confidence level was used in this estimate?(Hint: Work backwards from the margin of error to find the critical value.)

1. approximately 90%
2. Approximately 80%
3. Approximately 99%
4. Approximately 95%
5. It cannot be determined with the information given.