2.28 A term often used in solar energy research is heating-degree-days. This concept is related to the difference between an indoor temperature of 65°F and the average outside temperature for a given day. An average outside temperature of 5°F gives 60 heating-degree-days. The annual heating-degree-

day normals for several Nebraska locations are shown on the accompanying stem-and-leaf display constructed using MINITAB.

a. What is the meaning of “Leaf Unit  10”?

b. List the first four data values.

c. List all the data values that occurred more than once.

Stem-and-leaf of C1 N  25 Leaf Unit  10 2 60 78 7 61 03699 9 62 69 11 63 26

(3) 64 233 11 65 48 9 66 8 8 67 249 5 68 18 3 69 145