Answer:
you would need a 93.5% grade to get an average of 90%
Explanation:
You add up all the numbers then dived by amount of numbers added. so when you do (94.5%+87.4%+85.1%)/3 you get 89% so I kept doing numbers in the 90's to see what number I would need and once i added up 94.5%+87.4%+85.1%+93.5% you would then divide by 4 and get .901. That would end up being a 90.1% grade