Measuring specimen of nylon yarn from two spinning machines. It was found that 8 specimens from the Ist machine have a mean diameter of 9.67 with standard deviation 1.81, while 10 specimens from the IInd machine have mean 7.43 with standard deviation 1.48. Assuming that the population samples are normal and have same variance test. The null hypothesis is M M = 1.5 against the alternative hypothesis M M 1.5 at the level of significance 0.05?