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Question 939949: The mean of a set of n numbers is 12, and the mean of a set of 3n numbers is 6. What is the mean when the two sets are combined? Express your answer as a decimal to the nearest tenth.
Answer by laoman(51)   (Show Source):
You can put this solution on YOUR website! The mean of a set of n numbers is 12, and the mean of a set of 3n numbers is 6. What is the mean when the two sets are combined? Express your answer as a decimal to the nearest tenth.
Mean is Total/frequency
From the first statement,
Freq = n, Mean is 12, Therefore Total1 = Mean * freq = 12n
From the second statement,
Freq =3n, Mean = 6, Total2 = 18n
Mean of the two sets combined
= (Total1 +Total2) / (freq1+freq2)
= (12n+18n)/(3n+n)
= 30n/4n
= 7.5
( to the nearest tenth)
QED
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