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?
:
30 - 5 - 5 = 20 remaining students
:
Let x = av age of the remaining students
:
{{{((20x + 5(14) + 5(10)))/30}}} = 12
:
{{{((20x + 70 + 50))/30}}} = 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