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There were 200 fishes in an aquarium, 99% of which were red. How many red fishes must be removed to make the percentage of red fishes to 98%?
Hi Aditya,
The total number of fishes in the aquarium are 200. We have been given that 99 percent of these are red. So the number of red fishes would be .99*200 = 198.
Now let's say that after removing 'k' red fishes, we have 98 percent red fishes in the aquarium.
So we have
198 - k = .98( 200 - k)
=> 198 - k = 196 - .98k
=> .02k = 2
=> k = 100
Thus, we need to remove 100 red fishes to make their percentage 98%.
Hope that helps. You can also download CAT formulas pdf
Aditya answered it well, Download Inequalities formulas CAT pdf which might help for you CAT preparation.
The total number of fishes in the tank is 200. The number of red
fish is 99% of 200 (i.e., the number of red fishes is ((99/100)*100)=198.
Therefore the number of non-red fish is 2 (200-198).
The question says that after taking some number of red fish outside, the % of red fish in the tank becomes 98%.
Taking the non-red fish in the consideration, the same two fish which is 1% before removing the red colour fish becomes 2% now.
Just a simple common sense now, What is the number of fish in the tank when 2 fish makes 2%? Yup its 100. There is total of 100 fish now, where 2 fish is non-red fish so the remaining will be red fish.
Before taking the red fishes outside the total number of fishes is 200 and now it is 100, so the number of red fishes taken out is 100.
