A pupil's marks were wrongly entered as 85 instead of 45. Due to that the average marks for the class got increased by half. The number of pupils in the class is :  Choose the correct choice
A) 30 B) 80 C) 20 D) 25 E) 26
Let there be x pupils in the class.   Total increase in marks = (X*1/2) = X/2.   X/2 = (85 - 45)   =&gt; X/2 = 40   =&gt; X = 80.   ANSWER:80
<result>B</result>
A pupil's marks were wrongly entered as 85 instead of 45. Due to that the average marks for the class got increased by half. The number of pupils in the class is :