In a class, the average score of thirty students on a test is 69. Later on, it was found that the score of one student was wrongly read as 88 instead of 58. The actual average score is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e 68
Let the score of students be x1, x2, x3 ........................x30
The average score of 30 students = 69
So,
⇒ (x1 + x2 + x3 ........................x30) / 30 = 69
⇒ (x1 + x2 + x3 ........................x30) = 69 × 30
⇒ (x1 + x2 + x3 ........................x30) = 2070
After correcting the score of one student to 58
The new sum, (x1 + x2 + x3 ........................x30) = 2070 - 30 = 2040
New average = (x1 + x2 + x3 ........................x30) / 30
= 2040 / 30
= 68