SOLUTION: If the average (arithmetic mean) of k and 7k is 60, then k = a)7.5 b) 8 c) 9.5 d) 15

Question 275524: If the average (arithmetic mean) of k and 7k is 60, then k =
a)7.5 b) 8 c) 9.5 d) 15

Answer by fwm5007(5) (Show Source): You can put this solution on YOUR website!
To find the average you add the numbers together and divide by how many numbers there were. For instance if you had 2 and 4, you would add 2+4=6 and divide 6/2 which would give you an average of 3. In this problem you have the average and are working backwards in a sense. Your numbers are K and 7K. Those added together and then divided by 2(since there is only 2 numbers together) will equal the average given of 60. Set up the equation like this:
(7K + K)/2=60
Multiply each side by 2:
7K + K =120
Add the like terms
8K = 120
Divide by 8:
K = 15
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