<p>An alpaca breeder wants to produce fleece which is extremely fine. In 2008, his herd had mean fineness $22.3$ microns with standard deviation $\sigma $ microns. The standard deviation remains relatively constant over time. In 2012, a sample of $80$ alpacas from the herd was randomly selected, and the mean fineness was $21.2$ microns.</p>
<p>Find the range of values of the standard deviation which will indicate a significant change in mean fineness at the $5%$ two-tailed significance test.</p>

An alpaca breeder wants to produce fleece which is extremely fine. In 2008, his herd had mean fineness $22.3$ microns with standard deviation $\sigma $ microns. The standard deviation remains relatively constant over time. In 2012, a sample of $80$ alpacas from the herd was randomly selected, and the mean fineness was $21.2$ microns.

Find the range of values of the standard deviation which will indicate a significant change in mean fineness at the $5%$ two-tailed significance test.

EJC Hypothesis Testing Tutorial Q12

EJC Hypothesis Testing Tutorial Q12

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