To help make decisions about advertising potential for your website, you are interested in learning the average amount of time visitors to your website spend on the site. You manage to collect a month’s worth of data that includes 9,872 website visits and their duration. The data are in attached.

1. Build a 90% confidence interval for the mean visit duration for all visitors to your website. Explain what this confidence interval means.
2. Build a 95% confidence interval for the mean visit duration for all visitors to your website. Explain what this confidence interval means.
3. Build a 99% confidence interval for the mean visit duration for all visitors to your website. Explain what this confidence interval means.
4. Is there reason to believe your confidence levels are inaccurate? If so, what assumption(s) may be inaccurate?