There are 200 fishes in a pond, 99% of which were red. How many red fishes must be removed to make the percentage of red fishes are 98%? Thanks in advace
logic or math on numbers
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elementary-number-theory
arithmetic
contest-math
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1Any ideas? What did you try? – 2017-02-18
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099% red means, 198 are red. – 2017-02-18
1 Answers
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Total number of red fishes $= \frac {99}{100} \times 200 =198 $
Number of red fishes removed $=x$
New total number of fishes $= 200 - x$
New total number of red fishes = $198 - x$
Now, relate to the new percentage, i.e, 98%
New number of red fishes $= \frac {98}{100} \times (200-x) =198-x $
↑SPOILERS↓
x = 100