Question
The average age of (x + 4) students of a class is 18 years.
If the 54 years old class teacher is also included then average age of the class gets increased by two years. Find x% of 300.Solution
Total age of students = 18(x + 4) years
According to question,
[18(x + 4) + 54] = (18 + 2)(x + 4 + 1)
18x + 72 + 54 = 20x + 100
20x – 18x = 126 – 100
x = 13
So, 13% of 300 = 39
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