Can you please answer this question using clear detailed steps as I'm having trouble with this statistics topic.

11 The weekly productivity of a group Is measured [in terms of number of hours worked] for a 15- week period. The results were: [19.8, 19.1, 14.9, 1.5, 15.4, 15.4, 11.4, 14.1, 11.5, 163, 15.9 15.5, 19.5 ,12.?, 11.91 hours. Assume that the work hours for this group are normally distributed. Construct a 9596 and a 99% two-sided condence interval on the mean for the productivity of the group. [2 Marks]