The actual voltages of power packs labeled as 12 volts are as follows: 11.77, 11.90, 11.64, 11.84, 12.13, 11.99, 11.77.
Referring to Table 1 a confidence interval for this sample would be based on the t distribution with __________ degrees of freedom.
Referring to Table 1, the critical value for a 99% confidence interval for this sample is __________.
Referring to Table 1, a 99% confidence interval for the mean voltage of the power packs is from __________ to __________.