A psychologist is interested in knowing whether adults who were bullied as children differ from the general population in terms of their empathy for others. On a questionnaire designed to measure empathy, the mean score for the general population is 35.66. Random sampling of 140 scores obtained from individuals who were bullied yielded a mean of 33.64 and a standard deviation of 17.74. (Use these numbers only for this question!) What is the z-value or t-value you obtained (your test statistic)? (numeric value only, including negative sign if required)