Understanding Basic Statistics 6th Edition by Charles Henry Brase,Corrinne Pellillo Brase

تمرين 9

Environmental: Land Formations Arches National Park is located in southem Utah. The park is famous for its beautiful desert landscape and its many natu­ral sandstone arches. Park Ranger Edward McCarrick started an inventory (not yet complete) of natural arches within the park that have an opening of at least 3 feet. The following table is based on information taken from the book Canyon Country Arches and Bridges by F. A. Barnes. The height of the arch opening is rounded to the nearest foot.

For an arch chosen at random in Arches National Park, use the preceding information to estimate the probability that the height of the arch opening is
(a) 3 to 9 feet tall
(b) 30 feet or taller
(c) 3 to 49 feet tall
(d) 10 to 74 feet tall
(e) 75 feet or taller