SOLUTION: The average of seven numbers is 39 and the average of three of them is 27 find the average of the other four

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Question 1122556: The average of seven numbers is 39 and the average of three of them is 27 find the average of the other four
Answer by ikleyn(52817) About Me  (Show Source):
You can put this solution on YOUR website!
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If the average of 7 numbers is 39, then the sum of these numbers is 7*39.


If the average of 3 numbers is 27, then the sum of these numbers is 3*27.


Then the sum of 4 (four) remaining numbers is the difference  7*39 - 3*27.


Then the average of these 4 numbers is  %287%2A39+-+3%2A27%29%2F4 = 48.


Answer.  The average of these 4 numbers is  48.

Solved.

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I explained the solution in all details, so it took 4 lines.

But the person who is familiar with the subject, must solve such problems in ONE LINE: 

     The average of these 4 numbers is  %287%2A39+-+3%2A27%29%2F4 = 48.
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