Question

The average grade of a section of $20$ students is $66\%$ and that of another section of $15$ students is $70\%$. What is the combined mean grade?

• A. $66.7\%$
• B. $67.7\%$
• C. $68.7\%$
• D. $69.7\%$

Answer 1

Answer: (B)

$67.7\%$

$\Rightarrow$ Average grade of $20$ students is $66\%$.

$\therefore$ Total grade of $20$ students $=20\times 66\%=1320\%$

$\Rightarrow$ Average grade of $15$ students is $70\%$.

$\therefore$ Total grade of $15$ students $=15\times 70\%=1050\%$

$\Rightarrow$ Total students $=20+15=35$

$\Rightarrow$ Total grade of $35$ students $=1320\%+1050\%=2370\%$

$\therefore$ Required mean grade $=\frac{2370\%}{35}=67.7\%$