Practice: Determining Confidence Intervals for Variation $($p$.292)$

$7.$ The voltage of a power supply is of interest to a team. Voltage is assumed to be normally distributed. The voltages of seven randomly selected observations are: $10\mathrm{.}37,11\mathrm{.}50,9\mathrm{.}80,10\mathrm{.}65,11\mathrm{.}95,10\mathrm{.}15,9\mathrm{.}52.$ Find the $95\%$ confidence interval on the population variance of voltage.