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Let the mean and variance of 12 observat...

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

A

316

B

317

C

314

D

315

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