If Brittany has a 49.7% grade average then for her final exam that is worth 20% of the grade and she gets a 90% what would her final grade be?

Grade average is worth (100-20)=80%

Final is worth 20%.
Overall average
=49.7%*80%+90%*20%
=57.76%

To determine Brittany's final grade, we need to calculate the weighted average of her current grade and her final exam grade. Here's how we can do that step-by-step:

1. Calculate the weighted average of Brittany's current grade and her final exam grade:
- Multiply Brittany's current grade average (49.7%) by the weight of her current grade (80%, since it is worth 80% of the total grade). This gives us: 49.7% * 80% = 39.76%.
- Multiply Brittany's final exam grade (90%) by the weight of the final exam grade (20%, since it is worth 20% of the total grade). This gives us: 90% * 20% = 18%.

2. Add the weighted scores together to get the final grade:
- Add the weighted average of her current grade (39.76%) and the weighted final exam grade (18%): 39.76% + 18% = 57.76%.

Therefore, Brittany's final grade would be 57.76%.