The Wind Mountain excavation site in New Mexico is an important archaeological location of the ancient Native American Anasazi culture. The following data represent depths (in cm) below surface grade at which significant artifacts were discovered at this site (Reference: A. I. Woosley and A. J. McIntyre, Mimbres Mogollon Archaeology, University of New Mexico Press). 85 45 75 60 90 90 115 30 55 58
78 120 80 65 65 140 65 50 30 125
75 137 80 120 15 45 70 65 50 45
95 70 70 28 40 125 105 75 80 70
90 68 73 75 55 70 95 65 200 75
15 90 46 33 100 65 60 55 85 50
10 68 99 145 45 75 45 95 85 65
65 52 82

Required:
a. Find the class width.
b. Make a frequency table showing class limits, class boundaries, midpoints, frequencies, relative frequencies, and cumulative frequencies. (Give relative frequencies to 4 decimal places.)