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The students of three classes are in the ratio 3 : 4 : 5. If 15 students are increased in each class, then ratio changes to 6 : 7 : 8. The total number of students before the increase was

A) 70
B) 90
C) 120
D) 60

Correct Answer:




D) 60

Description for Correct answer:

Let the number of students be 3x, 4x and 5x.
Then (3x + 15) : (4x + 15) : (5x +15) = 6 : 7 : 8

\( \Large \frac{3x + 15}{6} = \frac{4x + 15}{7} \)

= \( \Large\frac{5x + 15}{8} \)

= > 7(3x +15) = 6(4x + 15)
X = 5
Total number of students before increase = >12x = 60

Part of solved Ratio and Proportions questions and answers : >> Aptitude >> Ratio and Proportions

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