GATE CSE 2014 Set 3 | Question: GA-5

Question

The table below has question-wise data on the performance of students in an examination. The marks for each question are also listed. There is no negative or partial marking in the examination.

$$\begin{array}{|c|c|c|c|c|} \hline \textbf{Q No.} & \textbf{Marks} &\textbf{Answered}&\textbf{Answered}&\textbf{Not}\\&&\textbf{ Correctly} &\textbf{Wrongly} & \textbf{Attempted} \\\hline \text{1} & \text{2} &\text{21} &\text{17} &\text{6}\\\hline \text{2} & \text{3} &\text{15} & \text{27}& \text{2}\\\hline \text{3} & \text{2} &\text{23} & \text{18} & \text{3}\\\hline \end{array}$$

What is the average of the marks obtained by the class in the examination?

• A. $1.34$
• B. $1.74$
• C. $3.02$
• D. $3.91$

Answer 1

The question paper has only $3$ questions. There are $3$ ways a student can attempt a question. 

1. Attempt correctly
2. Attempt wrongly
3. Not attempted

Each row lists number of students who attempted the question correctly , wrongly and who did not attempt.
Sum of these, of any row gives the total strength of class , $21+17+6 = 44.$

Average  marks obtained by the class in the examination,

$= \dfrac{\text{(Total marks(Q1)}+\text{Total marks(Q2)}+\text{Total marks(Q3)})}{\text{Total strength of class}}$
$=\dfrac{((2\times 21)+(3\times 15)+(2\times 23))}{44}$
$=\dfrac{133}{44}= 3.02$

Note : There is no negative or partial marking for the wrongly attempted and the non-attempted questions.

Correct Answer: $C$