A pupil's marks were wrongly entered as 83 instead of 63. Due to that the average marks for the class got increased by half (1/2). The number of pupils in the class is: Choose the correct choice from the following.
A) 10  B) 20  C) 30  D) 40  E) 50
x pupils in class   total increase = (x*1/2) = x/2   x/2=(83-63)= 
<gadget id="calculator">(83-63)</gadget>
<output>20</output>
20 x= 40   ANSWER 40
<result>D</result>
A pupil's marks were wrongly entered as 83 instead of 63. Due to that the average marks for the class got increased by half (1/2). The number of pupils in the class is: