Question: A random sample of 12 hollyhock plants, grown from the seeds in a particular packet, was taken, and the height of each plant was measured, in m. The results are summarized \(\sum{{{x}_{i}}}=28.43\), \(\sum{x_{i}^{2}}=88.4704\). Making a suitable assumption about the distribution of heights, which should be stated, find a 90% confidence interval for the mean height of hollyhock plants grown from that packet.