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Let the mean and variance of 12 observations be 2 9 and 4 respectively. Later on, it was observed that two observations were considered as 9 and 10 instead of 7 and 14 respectively. If the correct variance is n m , where m and n are coprime, then m + n are coprime, then m + n is equal to

1. 315
2. 316
3. 314
4. 317

Correct answer: 317

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