The compressive strength of concrete is normally distributed. A random sample of 14 concrete specimens from Factory 1 yields a sample mean equal to 1,216.9 pounds per square inch (psi) and a sample variance of 868.6 psi2. A random sample of 13 concrete specimens from Factory 2 yields a sample mean equal to 1,349.6 psi and a sample variance of 891.0 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 and assume population variances are equal.