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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.

Q No. Marks Answered Correctly Answered Wrongly Not Attempted
$1$ $2$ $21$ $17$ $6$
$2$ $3$ $15$ $27$ $2$
$3$ $2$ $23$ $18$ $3$

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

  1. $1.34$
  2. $1.74$
  3. $3.02$
  4. $3.91$
asked in Numerical Ability by Veteran (107k points)
edited by | 840 views

1 Answer

+13 votes
Best answer

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.

answered by Active (3.7k points)
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