g a medical researcher wants to determine whether the usage of marijuana has an effect on a person's stress level. to perform this experiment, the researcher took a random sample of 10 subjects. each person's stress level was measured on a scale from 1-10 before the usage of marijuana. then each person's stress was measured again after using marijuana for five weeks. the average difference between the pair of measurements was found to be 3.5 with a standard deviation of the differences to be 3.30. what would be the calculated test statistic for this experiment?