Question: There are some boys and girls in a room. The square of the number of the girls is less than the square of the number of boys by 28. If there were 2 more girls, the number of boys would have been the same as that of the girls. The total number of boys and girls in the room are
Options:
A) 56
B) 14
C) 10
D) 7
Show Answer
Answer:
Correct Answer: B
Solution:
- Let the number of boys and girls in the room be x and y, respectively.
According to the question,
$ x^{2}-y^{2}=28 $
and $ x=y+2 $
$ x-y=2 $
Now, $ x^{2}-y^{2}=(x-y)(x+y)=2(x+y) $
$ \Rightarrow $ $ 28=2(x+y) $
$ \Rightarrow $ $ x+y=14 $
$ \therefore $ Total number of boys and girls $ =14 $