Question

I have a 62,75,90 on my history exams what do I need on the fourth one to have a mean of 80

Answer 1

mean of the 5 is the average
lets solve for what score gets 80
and lets say last score is x

so

(sum of scores)/4=80
(62+75+90+x)/4=80
(227+x)/4=80
times 4 both sides
227+x=320
minus 227 from both sides
x=93
yo need a 93
good luck