Answer : Option B

Explanation :

$MF#%\text{Total weight of students in division A = }36 \times 40\\\\
\text{Total weight of students in division B = }44 \times 35\\\\
\text{Total students = }36 + 44 = 80\\\\
\text{Average weight of the whole class = }\dfrac{\left(36 \times 40 \right)+\left(44 \times 35 \right)}{80}\\\\
= \dfrac{\left(9 \times 40 \right)+\left(11\times 35 \right)}{20}=\dfrac{\left(9 \times 8\right)+\left(11\times 7\right)}{4}=\dfrac{72+77}{4}=\dfrac{149}{4}=37.25$MF#%