Question

Marks obtained by a student in Mathematics in three monthly tests are 85, 60 and 75 resp. And in annual exams he got 95 marks. Weightage of monthly tests are same where as weightage of annual exams is double that of monthly exams. Find the mean weightage of marks in Mathematics.

Answer 1

According to question, $x_1=85,x_2=60,x_3=75,x_4=95,$
and $w_1=1,w_2=1,w_3=1,w_4=2$
$\overline{X}=\frac{\sum x_i{w}_i}{\sum w_i}$
$=\frac{w_1{x}_1+w_2{x}_2+w_3{x}_3+w_4{x}_4}{w_1+w_2+w_3+w_4}$
$=\frac{1\times 85+1\times 60+1\times 75+2\times 95}{1+1+1+2}$
$=\frac{410}{5}=82$