Your research group has been hired to determine if college men and women drink different amounts of soft drinks at Illinois State University. After a careful study, your group has determined that males drink an average of 8.50 sodas per week with a standard deviation of 0.5 whereas female students drink an average of 8.25 soft drinks per week with a standard deviation of 2.0 sodas. The sample size of males is 200 and the sample size of females is 150. Based on this information, your group calculates the z-score to be [____]