# Question

The diameter of the Douglas ﬁr tree is measured at a height of 1.37 meters.The following data represent the diameter in centimeters of a random sample of 12 Douglas ﬁrs in the western Washington Cascades.

(a) Obtain a point estimate for the mean and standard deviation diameter of a Douglas ﬁr tree in the western Washington Cascades.

(b) Because the sample size is small,we must verify that the data come from a population that is normally distributed and that the data do not contain any outliers. The ﬁgures show the normal probability plot and boxplot. Are the conditions for constructing a conﬁdence interval for the population mean diameter satisﬁed?

(c) Construct a 95% conﬁdence interval for the mean diameter of a Douglas ﬁr tree in the western Washington Cascades.

(a) Obtain a point estimate for the mean and standard deviation diameter of a Douglas ﬁr tree in the western Washington Cascades.

(b) Because the sample size is small,we must verify that the data come from a population that is normally distributed and that the data do not contain any outliers. The ﬁgures show the normal probability plot and boxplot. Are the conditions for constructing a conﬁdence interval for the population mean diameter satisﬁed?

(c) Construct a 95% conﬁdence interval for the mean diameter of a Douglas ﬁr tree in the western Washington Cascades.

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