A tank contains 200 fish and 99% of them are tetras. How many tetras should be removed so that exactly 98% of the fish in the tank are tetras?

Guest Nov 5, 2019

#1**+2 **

200 (.99) number of tetras originally now subtrac x from that number

200(.99) - x the TOTAL number of fish also gets decreases to 200 - x

The tetras remaining in the tank 200(.99) - x

divided by the total number of fish 200- x = 98 %

[200(.99) - x ] / (200-x) = .98 solve for 'x' the number of tetras to remove....

ElectricPavlov Nov 5, 2019

#2**+1 **

If 99% are tetras.....then .99 * 200 = 198 are tetras

Let N be the number of tetras to be removed....so

[ 198 - N ] / [ 200 - N ] = .98 cross-multiply

198 - N = .98 [ 200 - N ]

198 - N = 196 - .98N Add N to both sides......subtract 196 from both sides

2 = .02N Divide both sides by .02

100 = N = the number to be removed

Proof

[ 198 - 100 ] / [ 200 - 100] =

98 / 100 = .98 = 98%

CPhill Nov 5, 2019