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

Exercise 20

Ecology: Sand Dunes At wind speeds above 1000 centimeters per second (cm/sec), significant sand-moving events begin to occur. Wind speeds below 1000 cm/sec deposit sand, and wind speeds above 1000 cm/sec move sand to new locations. The cyclic nature of wind and moving sand determines the shape and location of large dunes (Reference: Hydraulic, Geologic, and Biologic Research at Great Sand Dunes National Monument and Vicinity, Colorado, Proceedings of the National Park Service Research Symposium). At a test site, the prevailing direction of the wind did not change noticeably. However, the velocity did change. Sixty wind speed readings gave an average velocity of
= 1075cm/sec Based on long-term experience, can be assumed to be 265 cm/sec.
(a) Find a 95% confident interval for the population mean wind speed at this site.
(b) Interpretation Does the confidence interval indicate that the population mean wind speed is such that the sand is always moving at this site Explain.