Firstly, no formal survey is done which is a good choice by Carter. Gender wise salary is not a wise decision to make rather job department would be a good choice that way job evaluation can be done.
Paying 10% more than the prevailing rates is sensible. 5 steps in making rational pay plans are where primarily informal and formal salary survey is done. Then what others are paying is found out. Finally, after comparison, similar salary for similar jobs is paid. Later wage curve can be used to pay rates for each job. Pay ranges are to be developed for motivating high-performance employees.
Paying more according to gender is unfair. That should be ensured to be changed. Carters decision of paying 10% more than the prevailing rates is a sound one since it will actually reduce turnover and also create loyalty by them towards the organization.