Out-of-box Survey Designer doesn't support weighted scoring per answer choice. ServiceNow's intended solution is the Assessment module, which does support weights but is harder to manage.
Most common workaround if you want to stay with Survey Designer: create a custom lookup table mapping each answer choice to a numeric weight, then write a Business Rule on survey_response that calculates the total score on submission and stores it in a custom field.
Alternatively, some teams handle the weighting at the reporting layer using Performance Analytics, applying weights at query time rather than on the record itself.
