The tensile adhesion of each of 20 randomly selected specimens of a metal tested. The resulting measurements (in megapascals). Use them to calculate a 90% condence interval for the true mean tensile...

The tensile adhesion of each of 20 randomly selected specimens of a metal tested. The resulting measurements (in megapascals). Use them to calculate a 90% condence interval for the true mean tensile adhesion strength of the metal.

tensile adhesion of 20 specimens:

11.4   11.9    13.6     8.8     19.5

15.8   16.7    17.6     14.1    11.4

11.9   12.7      7.9     18.5    15.4

15.4    7.5     14.9     10.1    19.8

Using Excel, Total sum of 20 specimen measurements= 274.9

Average = 13.745

Use the given amounts to find the 90% confidence interval of the true mean.