SATHEE: Quantitative Aptitude Ques 2347

Quantitative Aptitude Ques 2347

Question: The ratio of the numbers of boys and girls in a school was 5: 3. Some new boys and girls were admitted to the school, in the ratio 5: 7. At this the total number of students in the school became 1200 and the ratio of boys to girls changed to 7: 5. The number of students in the school before new admission was

Options:

A) 700

B) 720

C) 900

D) 960

Show Answer

Answer:

Correct Answer: D

Solution:

Let number of boys and girls in the school before new admissions are 5x and 3x, respectively. Now, let 5y and 7y boys and girls are admitted in the school.

$ \therefore $ $ 5x+3x+5y+7y=1200 $

$ \Rightarrow $ $ 8x+12y=1200 $ … (i) Also, $ \frac{5x+5y}{3x+7y}=\frac{7}{5} $

$ \Rightarrow $ $ 25x+25y=21x+49y $

$ \Rightarrow $ $ x=6y $ … (ii) From Eqs. (i) and (ii), we get $ x=120 $ and $ y=20 $ Hence, total number of students in school before new admissions $ =5x+3x=8x=8\times 120=960 $

Quantitative Aptitude Ques 2346

Quantitative Aptitude Ques 2348

Quantitative Aptitude Ques 2347

Options:

Answer:

Solution:

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