The z-score obtained from the analysis for March 2015 was 30.17. The value is a lot higher than the larger value usually encountered in z-tables (i.e. 3.84). Based on the z-score, there are enough evidence to reject the null hypothesis that young people are less likely to commute by bike compared to older ones, in significance level a=0.05. Similarly, the z-score for July 2015 was 43.92 (even more significant), again rejecting the null hypothesis, and showing robustness of the statistic in seasonal change.