SOLUTION: If the average (arithmetic mean) of six numbers is 28 and the average of two of these numbers is 18, what is the average of the other four numbers? a) 29 b) 30 c) 31 d) 32 e)

Algebra ->  Average -> SOLUTION: If the average (arithmetic mean) of six numbers is 28 and the average of two of these numbers is 18, what is the average of the other four numbers? a) 29 b) 30 c) 31 d) 32 e)       Log On


   

Question 885833: If the average (arithmetic mean) of six numbers is 28 and the average of two of these numbers is 18, what is the average of the other four numbers?
a) 29
b) 30
c) 31
d) 32
e) 33
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
WITH CALCULATOR:
For the six numbers:
average=SUM%2F6=28--->SUM=28%2A6=168

For the two numbers averaging 18:
average=sum%2F2=18--->sum=18%2A2=36

The sum of the other four numbers is
168-36=132 , and the average of those four numbers is
152%2F4=highlight%2833%29

IN MY HEAD:
Those two numbers averaging 18 are (on the average)
28-18=10 lower than average.
The 2%2A10=20 units missing must have been made up by the other 4 numbers
That means that the average of those other 4 numbers must be
20%2F4=5 units higher than the average of all six numbers.
So the average of the other four numbers is
28%2B5=33