92. Tom and Joe sell cakes. Tom motivates Joe mentioning that they will sell a minimum of 20 cakes per day if the outside temperature exceeds 80 o F. From a sample, whose population is assumed to follow a Normal Distribution, taken for 20 days at 80 degrees or more an average of 13.6 pots per day were sold with a Standard Deviation of 0.7 pots. The statistical Degree of Freedom for this example are