Use p-values to test the null hypothesis of equal means against an alternative that 2 > 1

Question:

Use p-values to test the null hypothesis of equal means against an alternative that μ2 > μ1 when sample means of 1 and 2 are found from samples of size n1 and n2 with sample variances s21 and s22. Use a one-tailed test. State the significance level of the test.
1 = 70.0, 2 = 70.4, n1 = 500, n2 = 500, s21 = 25.0, s22 = 25.0. The difference between means is 10 times smaller, but the populations are 10 times larger than in Exercise 1. Why is the significance level different?