A) 700
B) 720
C) 900
D) 960
Correct Answer: D
Solution :
Let the original number of boys and girls be 5x and 3x respectively and that of new boys and girls be 5y and 7y respectively. \[\therefore \] \[5x+3x+5y+7y=1200\] \[\Rightarrow \] \[2x+3y=300\] ?(i) and \[\frac{5x+5y}{3x+7y}=\frac{7}{5}\] \[\Rightarrow \] \[25x+25y=21x+49y\] \[\Rightarrow \] \[4x=24y\] \[\Rightarrow \] \[x=6y\] From Eq. (i), we get \[4x+6y=600\] \[\Rightarrow \] \[5x=600\]\[\Rightarrow \]\[x=120\] Original number of students\[=8x=960\]You need to login to perform this action.
You will be redirected in
3 sec