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If both the mean and the standard deviation of 50 observations x 1 , x 2 ,..., x 50 are equal to 16, then the mean of (x 1 – 4) 2 , (x 2 – 4) 2 ,....., (x 50 – 4) 2 is :

1. 400
2. 480
3. 380
4. 525

Correct answer: 400

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