For a group of 200 candidates, the mean find the standard deviations of scores were found to be 40 and 15 respectively. Later on, it was discovered that the scores of 43 and 35 were misread as 34 and 53 respectively. Find the correct mean and standard deviation.

Question

Philoid · Accepted Answer

To Find: Find the correct mean and standard deviation.

Explanation: Here, n=200,

X =

Since, the score was incorrect,

Now, The sum is incorrect

Corrected

8000-7

The correct score is 7993

So, The mean of correct score =

Mean = 39.95

Now, Standard variance = 15

Since, Variance =

Variance = 255

X =

255 =

Now, the correct
-34²-53²+43²+35²

365000-1156-2809+1849+1225

Corrected Variance =

1820.54-1596.40

Corrected variance =224.14

Now, Corrected Standard Deviation =

Correct Deviation is 14.97