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The compressive strength of concrete is normally distributed. A random sample of 11 concrete specimens from...

The compressive strength of concrete is normally distributed. A random sample of 11 concrete specimens from Factory 1 yields a sample mean equal to 1,221.3 pounds per square inch (psi) and a sample variance of 882.0 psi2. A random sample of 11 concrete specimens from Factory 2 yields a sample mean equal to 1,441.2 psi and a sample variance of 856.1 psi2.  

If you do a test of hypothesis to see if the means of the concretes from Factory 1 and Factory 2 are equal or not, what is the numerical value of the test statistic? Express your answer to two decimal places.

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