The Slant Shear Test (SST) is a widely used test for evaluating the bond of resinous repair materials to concrete. It was applied to two random samples of concrete slabs which were finshed in different ways. Population 1 has a smooth finish while Population 2 has a more textured finish. The sample mean shear strength ( in N/mm2) and sample standard deviation for the smooth finish sample of size 138 from were 18.17 and 1.78, respectively. The sample mean and variance in shear strenth for a random sample of size 110 hand-chiseled specimens, were were 21.66 and 3.21. Find a 95% confidence intervalul M2, the true mean difference in shear strengths.