A random sample of 15 students who got a GPA between 3.5−4.0 in last semester were asked the number of hours they study each night. For this group the sample mean was 2.6hr. and standard deviation 1.5hr. A second random sample 16 students who got a GPA of 2.0−2.5 were asked the same question. For this group the sample mean was 1.5hr. and standard deviation 1.3hr. By assuming that they have the same variances, do students who get higher grades study more hours at night?