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?

 34

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

R = sum of the 12 remaining values

R/12 = 30

R = 12*30

R = 360 is what the other 12 values add to

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

3, 12, 48, 384, 1536, 6144, 24576, 98304

step-by-step explanation:

just keep timing it by 4.

12.5 feet

step-by-step explanation: