# Percentage increase in ratios..

The question is:

Seats for Math,Physics and biology in a school are in ratio 5:7:8. There is a proposal to increase these seats by 40%,50% and 75% respectively.What will be ratio of increased seats?

Apparently I am currently increasing 5 by 40% and 7 by 50% and 8 by 75% . But this is not giving the correct answer. Any suggestions what should be done here ??

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Let number of seats be $5x,7x$ and $8x$. Number of seats after increment =$7x,21x/2,14x$. Therefore the new ratio is $14:21:28=2:3:4$.isn't this the answer?

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Yes that's the answer. I got till 7x,21x/2,14x but how did you get 14:21:28 ? –  Rajeshwar Jul 2 '12 at 10:21
multiply each by 2, since multiplication doesn't change the ratio and then divide each by 7 since division doesn't change the ratio either. –  Aang Jul 2 '12 at 10:23

To increase, first find the sum of ratio, 5 by 20 times 40 is 10 continue you'll get 10:17.5:30

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