Question 1054522
First test : {{{X}}}
Second test : {{{X+3}}}
Third test : {{{X+3+3=X+6}}}
Fourth test :{{{ X+6+3=X+9}}}
So then the average would be,
{{{A=(X+X+3+X+6+X+9)/4=(4X+18)/4=X+18/4=X+9/2}}}
Substituting,
{{{A=82+9/2}}}
{{{A=86.5}}}