While calculating the mean and variance of 10 readings, a student wrongly used the reading of 52 for the correct reading 25. He obtained the mean and variance as 45 and 16 respectively. Find the correct mean and the variance.
Given, Uncorrected mean is 40 and corrected SD is 10 and N = 100
To Find: Find the correct mean and SD
Explanation: Here,
Then,
The corrected sum of observation
So,
Variance =16
Incorrect
Correct
Correct
Correct SD,
Correct SD,
SD = 6.62
Variance = 6.62×6.62
Hence, Variance = 43.82