Question

find mean of 30 numbers given that the ten of them has mean 12 and mean of remaining 20 is 9

Answer 1

their final mean is 10

Answer 2

We have,mean of 10 numbers = 12⇒sum of 10 numbers10 = 12⇒sum of ten numbers = 120Mean of remaining 20 numbers = 9⇒sum of  20 numbers20 = 12⇒sum of 20 numbers = 240Sum of 30 numbers = 120 + 240 = 360Now, mean of 30 numbers = sum of 30 numbers30 = 36030 = 12
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