| The students in three classes are in the ratio 4: 6: 9. If 12 students are increased in each classes, the ratio changes to 7: 9: 12. Then, the total number of students in the three classes before the increase is [SSC (CGL) 2012] |
A) 95
B) 76
C) 100
D) 114
Correct Answer: B
Solution :
| Let the original number of students be \[4x,\]\[6x\] and \[9x.\] |
| According to the question, |
| \[\frac{4x+12}{6x+12}=\frac{7}{9}\] |
| \[\Rightarrow \] \[42x+84=36x+108\] |
| \[\Rightarrow \] \[42x-36x=108-84\] |
| \[\Rightarrow \] \[6x=24\]\[\Rightarrow \]\[x=4\] |
| \[\therefore \]Required number of students \[=19x=19\times 4=76\] |
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