The average of several exam scores is 80. One make-up exam was given. Included with the other scores, the new average was 84. If the score on the make up exam was 92, how many total exams were given?

A 3

B 2

C 4

D 5

Correct Answer: Option A

মনেকরি, পরীক্ষা সংখ্যা = x
প্রশ্নমতে, 84 (x + 1) - 80x = 92
⇒ 84x + 84-80x = 92
⇒ 4x = 8
∴ x = 2

অতিরিক্ত 1টি পরীক্ষাসহ মোট পরীক্ষা = 2 + 1 = 3