Problema Solution
The mean of 3 numbers is 7. The mean of 4 other numbers is 8. The mean of 5 other numbers is 11. What is the mean of all 12 numbers?
Answer provided by our tutors
The mean is the average of the numbers.
The mean of 3 numbers is 7
let S1 = the sum of the 3 numbers then
S1/3 = 7
S1 = 3*7
S1 = 21
The mean of 4 other numbers is 8.
let S2 = the sum of the 4 numbers then
S2/4 = 8
S2 = 8*4
S2 = 32
The mean of 5 other numbers is 11
let S3 = the sum of the 5 numbers then
S3/5 = 11
S3 = 11*5
S3 = 55
the sum of all 12 numbers is: S1 + S2 + S3
the mean of all 12 numbers is:
(S1 + S2 + S3)/12 = (21 + 32 + 55)/12 = 9
the mean of all 12 numbers is 9.
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