Problem 4 (25 points) Results of tests on concrete strengths made on two batches of concrete are summarized as: Batch 1: x1 = 60.34, $1 = 5.72 N/mm, n1 = 12. Batch 2: X2 = 54.23, $2 = 7.01 N/mm2, n2 = 10. Test whether the strength of the first batch is significantly higher than that of the second at the levels of significance a = 0.01 and a = 0.05. Assume population variances are equal