Two Sample t-Tests

The amount of a certain trace element in blood is known to vary with a standard deviation of 13.2 ppm (parts per million) for male blood donors and 8.9 ppm for female donors. Random samples of 65 males yield concentration means of 28, and 33 ppm for 43 female donors. Is the average difference between male and female concentrations statistically significant or due instead to random chance? Assume $\alpha = 0.05$