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!