Aresearcher would like to test whether a new teaching method enhances the concept understanding. in a paired sample t test, a random sample of 20 students were given a pre-test before a new method was introduced. after the new method was introduced , a post test was given. the differences of pre-test scores and post test scores ( d = post test score - pre test score) were recorded for all students. the sample mean difference and the standard deviation of differences for the 20 students were 2.82 and 3.7 respectively. what is the value of the t test statistic (for two decimal places) for the paired sample test?