Question 9 . 1 pts Go to artofstat.com, click on Web Apps, scroll down and open the Explore Coverage app. Change the tab at the top of the page to Confidence Interval for a Mean. Change the "Select shape of population distribution" drop down menu to Bell-shaped and use the default mean=50 and standard deviation=10. Under "Select sample size (n)" use the default of n=30 and under "Choose confidence level (in %)" use the default 95. Under "Select how many samples (of size n) you want to draw from the population" start with just 1. Click on "Draw sample(s)" and note that a confidence interval appears under the population graph. What does the green square in the middle of the interval represent? The population mean, mu, computed from all data points in the population. The sample mean, mu, computed from 30 observations. The population mean, x-bar, computed from all data points in the population. The sample mean, x-bar, computed from 30 observations