Chapter 15.4, Problem 14E

Refer to Exercise 15.6(a). Answer the question by using the Wilcoxon signed-rank test.

15.6 On clear, cold nights in the central Florida citrus region, the precise location of below-freezing temperatures is important because the methods of protecting trees from freezing conditions are very expensive. One method of locating likely cold spots is by relating temperature to elevation. It is conjectured that on calm nights the cold spots will be at low elevations. The highest and lowest spots in a particular grove yielded the minimum temperatures listed in the accompanying table for ten cold nights in a recent winter.

1. a Is there sufficient evidence to support the conjecture that low elevations tend to be colder? (Use the sign test. Give the associated p-value.)
2. b Would it be reasonable to use a t test on the data? Why or why not?