A course in physics is taught to 10 students by traditional method. Another group of 11 students was given the same course by means of another method. At the end of the semester, the same test was administered to each group. The 10 students under method A made an average of 82 with a standard deviation of 5, while the 11 students under method B made an average of 78 with a standard deviation of 6. Test the null hypothesis of no significant difference in the performance of the two groups of students at 5% level of significance.