Answer: Option D
Answer: (d)Required average = 30+${(28+31-82-13)}/50$ = 30 $(-36/50)$= 30 – 0.72 = 29.28 Aliter : Using Rule 27,If the average of n numbers is m later on it was found that two numbers a and b misread as p and q. The correct average = m +${\text"(a+b-p-q)"}/ \text"n"$.Here, n = 50, m = 30 a = 28, b = 31 p = 82, q = 13 Correct Average = m + ${\text"(a+b-p-q)"}/ \text"n"n$ = 30 +${(28+31-82-13)}/50$ = 30 +$({59-95}/50)$= 30 -$36/50$= 30 – 0.72 = 29.28