A student randomly selects 10 CDs at a store. The mean is 875 dol.pdf

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A student randomly selects 10 CDs at a store. The mean is 8:75 dollars with a standard deviation of 1:50: Construct a 95% con- ?dence interval for the population standard deviation, . Assume the data are normally distributed Solution (n-1)s2/(Xu2) < 2 < (n-1)s2/(XL2) Look up the chi square values from the tables X0.9752 With n-1=9 degrees freedom = 2.7 X0.0252 With n-1=9 degrees freedom = 19.023 s2=1.52=2.25 9*2.25/19.023 < 2 < 9*2.25/2.7 1.0645 < 2 < 7.5 1.03 < < 2.74.

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