Question

The average of 20 observations was
found to be 76.4. But later on it was
found that 56 was misread as 65. The
new correct average is
A) 77.3
B) 75.95
C) 76.9
D) 75.4
​

Answer 1

According to the question

Wrong numbers = 65

Correct numbers = 56

Difference = 65 - 56 = 9

Difference '9' effect the 20 observation. = 9/20=0.45

∵ Wrong average = 76.4

∴ Correct average = 76.4+ 0.45= 76.85