At wind speeds above 1000 centimeters per second (cm/sec), significant sand-movi
ID: 2947459 • Letter: A
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-two wind speed readings gave an average velocity of x = 1075 cm/sec. Based on long-term experience, ? can be assumed to be 265 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 1009 cm/sec upper limit 1140x Xcm/secExplanation / Answer
CI for 95%
n = 62
mean = 1075
z-value of 95% CI = 1.9600
std. dev. = 265
SE = std.dev./sqrt(n)
= 265/sqrt(62)
= 33.6550
ME = z*SE
= 1.95*33.6550
= 65.9627
Lower Limit = Mean - ME = 1075 - 65.9627 = 1009.03735 = 1009
Upper Limit = Mean + ME = 1075 + 65.9627 = 1140.96265= 1141
95% CI (1009, 1141)
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