Citibank, which has a major credit card division, has designed a promotion designed to encourage its customers to increase their current credit card usage. To test the effectiveness of this promotion, Citibank monitored the monthly credit card balances of 25 customers before and after the promotion was launched. The results can be found in the Excel file Citibank 1.xlsx. Using α = 0.05, perform a hypothesis test to determine if the median credit card balance was higher after the promotion than before the promotion.