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JEE Main 2007
Exam
JEE Main
Year
2007
Subject
Mathematics
Chapter
Statistics

JEE Main 2007 · Mathematics · Statistics

The average marks of boys in a class is 52 and that of girls is 42...

The average marks of boys in a class is 5252 and that of girls is 4242. The average marks of boys and girls combined is 5050. The percentage of boys in the class is

Options

  1. A4040
  2. B2020
  3. C8080
  4. D6060

Correct answer

C. 8080

Step-by-step solution

52x+42y=50(x+y)52 x+42 y=50(x+y) 2x=8y2 x=8 y ⇒xy=41\Rightarrow \frac{x}{y}=\frac{4}{1} and xx+y=45\frac{x}{x+y}=\frac{4}{5} ∴%\therefore \% of boys =80=80.
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