The bad debt ratio for a financial institution is defined to be the dollar value of loans defaulted divided by the total dollar value of all loans made. A random sample of six Ontario banks is selected and the bad debt ratios (in percentages) for these banks are:

7,4,6,7,5,8,

Compute and interpret a 95% confidence interval for the mean bad debt ratio. What needs to be true in order for this interval and interpretation to be valid?