Kaplan Q309 Glove Co - Labour efficiency planning variance

Hello, I am doing this question but I am having issues with the labour efficiency planning variance. Std hours used is fine = 3*12600 = 37800 My issue is with the revised std It says in the question that 15 minutes extra is needed for each pair due to a change in design. Therefore I would assume the revised std to be 3.15*12600=39690 But Kaplan has the revised std as 3.25*12600 How did they get the time of 3 hrs 25? Thank you!