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The students in three classes are in the ratio 2 : 3 : 5. If 20 students are increased in each
class, the ratio changes to 4 : 5 : 7. Originally the total number of students was :
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- 50
- 90
- 100
- 150
Correct Option: C
Let the original number of students in three classes be 2x, 3x and 5x respectively.
As given,
| = | ||
| 3x + 20 | 5 |
⇒ 10x + 100 = 12x + 80
⇒ 12x – 10x = 100 – 80
⇒ 2x = 20
| ⇒ x = | = 10 | |
| 2 |
∴ Total number of students originally
= 2x + 3x + 5x = 10x
= 10 × 10 = 100
