A local gamer has a theory that the average temperature of a bowl of soup served in a restaurant is more than 75 degrees. It is well known to have a symmetric distribution. A sample was collected to be:

87 90 65 96 65 66 72 74 75 75 77 88

Does a stem-and-leaf show that our data is symmetric? Regardless, perform a Wilcoxon Signed-Rank Test for testing this theory at 90%.