Question

The average marks, in a class of $30$ students, are found to be $45$. On checking two mistakes were found. After correction, if one student got $45$ marks more and another students got $15$ marks less, then the correct average marks are

• A. $45$
• B. $44$
• C. $47$
• D. $46$

Answer 1

Answer: (D)

$46$

Initial Average of marks $=$ $45$
Initial sum of marks $=$ $45\times 30$ $=$ $1350$
After correction marks of one increased by $45$ and other decreased by $15.$ Hence, the new sum of marks =$1350+45-15=1380$.
New average $=$ $\frac{1380}{30}$ $=46$.