Conclusion
We can see from the results presented from Figure 8 that the null hypothesis does not stand since Avg(customer_trip_duration) - Avg(subscriber_trip_duration) is greater than zero. I then need to test and see is this difference significant. I used a t-test for two means to confirm that the p-value is smaller than 0.05, indicating that the null hypothesis can be rejected. 
There are some weakness in my studies. First of all, all data is used without considering the effects of seasonality. Moreover, I only used data from two months. Probably using data from a bigger time window will disproves my results.