Citibike has been expanding in New York City over the past 5 years, and has locals and tourists as users. I've looked the Citbike ridership data from May 2016 to see if the fraction of rides taken by tourists on weekends is significantly higher than the fraction of tourists using this service on weekdays. After using a chi square test, I've concluded that ridership on weekends by tourists is indeed higher on weekends than weekdays, at significance level 0.05.