Question

The mean of eight numbers is 40 and the mean of other twelve different numbers is 30. What is the mean of all the twenty numbers?
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Answer 1

Answer:  34

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Work Shown:

S = sum of the first 8 numbers

S/8 = 40 is the mean of those first 8 numbers

S = 8*40

S = 320 so the first 8 numbers add to this value

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R = sum of the 12 remaining values

R/12 = 30

R = 12*30

R = 360 is what the other 12 values add to

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R+S = 360+320 = 680  is what all twenty values add to. Divide this by 20 to get the overall average

(R+S)/20 = 680/20 = 34