At wind speeds above 1000 centimeters per second cmsec signi

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. At a test site, the prevailing direction of the wind did not change noticeably. However, the velocity did change. Sixty-three wind speed readings gave an average velocity of

Solution

(a) Given a=1-0.95 =0.05, Z(0.025) = 1.96 (from standard normal table)

So the lower limit is

xbar -Z*s/vn = 1075 -1.96*285/sqrt(63) =1005

So the upper limit is

xbar +Z*s/vn =1075 +1.96*285/sqrt(63) =1145

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(b)Yes. This interval indicates that the population mean wind speed is such that the sand is always moving at this site.