Question

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-five wind speed readings gave an average velocity of x = 1075 cm/sec. Based on long-term experience, σ can be assumed to be 240 cm/sec.

(a) Find a 95% confidence interval for the population mean wind speed at this site. (Round your answers to the nearest whole number.)

lower limit	cm/sec
upper limit	cm/sec

(b) Does the confidence interval indicate that the population mean wind speed is such that the sand is always moving at this site? Explain.

No. This interval indicates that the population mean wind speed is such that the sand may not always be moving at this site.Yes. This interval indicates that the population mean wind speed is such that the sand may not always be moving at this site.    Yes. This interval indicates that the population mean wind speed is such that the sand is always moving at this site.No. This interval indicates that the population mean wind speed is such that the sand is always moving at this site.

Answer 1

Given
X bar	1075
μ	1000
σ	240
n	65

α=

0.05

CI
Zc	1.959964	+/-   NORM.S.INV(α/2)
Upper	1133.345	X bar + Zc*(σ/SQRT(n))
Lower	1016.655	X bar - Zc*(σ/SQRT(n))

a)

lower limit	1017 cm/sec
upper limit	1133 cm/sec

b)

No. This interval indicates that the population mean wind speed is such that the sand may not always be moving at this site.

wind speeds above 1000 cm/sec move sand to new locations(not in same site)