A valve manufacturer produces a butterfly valve composed of two semicircular plates on a common spindle that is used to permit flow in one direction only. The semicircular plates are supplied by a vendor with specifications that the plates be 2.37 millimeters thick and have a tensile strength of five pounds per millimeter. A random sample of 20 such plates is taken. Electronic calipers are used to measure the thickness of each plate; the measurements are given here. Assuming that the thicknesses of such plates are normally distributed, use the data to construct a 95% level of confidence for the population mean thickness of these plates. What is the point estimate? How much is the error of theinterval?

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2.4066 2.4579 2.6724 2.1228 2.3238 2.1328 2.0665 2.2738 2.2055 2.5267 2.5937 2.1994 2.5392 2.4359 2.2146 2.1933 2.4575 2.7956 2.3353 2.2699