Question 545829
theres alot of unknowns here...like what percentage is the lowest B for your class. some classes ive been in ranged for lowest: 84.5%, 80%, or 79.5%.
if i knew how many points made up that 81% and how many points made up the exam plus the lowest B% I could give you the exact percentage and points needed. but this question is to vague to answer.

this would be my best guess with the standard 80% being lowest B
{{{(81+81+81+x)/4=80}}}
{{{(243+x)/4=80}}}
{{{(243+x)=320}}}
{{{x=77}}}
so atleast a 77% on the exam