SOLUTION: The average age of 30 students in a class is 12 years. The average age of a group of 5 of the students is 10 years and that of another group of 5 of them is 14 years. Find the aver

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Question 726668: The average age of 30 students in a class is 12 years. The average age of a group of 5 of the students is 10 years and that of another group of 5 of them is 14 years. Find the average age of remaining students?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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The average age of 30 students in a class is 12 years.
The average age of a group of 5 of the students is 10 years and that of another group of 5 of them is 14 years.
Find the average age of remaining students?
:
30 - 5 - 5 = 20 remaining students
:
Let x = av age of the remaining students
:
%28%2820x+%2B+5%2814%29+%2B+5%2810%29%29%29%2F30 = 12
:
%28%2820x+%2B+70+%2B+50%29%29%2F30 = 12
multiply both sides by 30
20x + 120 = 30(12)
20x = 360 - 120
20x = 240
x = 240/20
x = 12 yrs, av age of remaining students