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Re: x percent of y percent of z is decreased by y percent . what [#permalink]

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23 Sep 2011, 04:15

I agree that you can get to answer directly, but many times the answers will be different ratio/multiple form of the answer, so you might need answer choices to work through. Also some times variables are too cluttery so some people with non-math background like me need numbers to work through.

x percent of y percent of z is decreased by y percent . what is the result? let x = 10, y =20 and z =1000. (x percent of y percent of z = 10% 0f 20% of 1000 ; 10 % of (20% of 1000) ; 10% of 200 =20.

20 is decreased by y percent. that is 20 is decreased by 20%. so 20 - (20/100* 20) = 16 Now target answer is 16, plug in values .

A)100XYZ - XY^2Z/1,000,000

(100 *10*20*1000 - 10.(20^2)1000)/ 10^6

> (20,000,000 - 400,000,0) /10^6 = 16 (target). you may need to check other answers but in this case the numbers I have picked are so distinct that it wont give same answer. so answer is A.

Sorry. I'm stuck because for me the right translation is

x/100 * y/100 * z = (1- y/100) or not ??

I'd resolve this question by math because is pretty straighforward than the strategy of target.

anyone can help me ??

Thanks a lot

It can be done by plug-in method though as you are doing with algebra I'll proceed with it.

x percent of y percent of z is decreased by y percent. What is the result?

Step by step: 1. \(y\) percent of \(z\) is \(\frac{y}{100}*z=\frac{yz}{100}\); 2. \(x\) percent of above value is \(\frac{x}{100}*\frac{yz}{100}=\frac{xyz}{10,000}\); 3. The above value is decreased by \(y\) percent: \(\frac{xyz}{10,000}*(1-\frac{y}{100})=\frac{xyz}{10,000}*(\frac{100-y}{100})=\frac{100xyz-xy^2z}{1,000,000}\) (for example 100 is decreased by 10 percent can be expressed as \(100*(1-\frac{10}{100})=100*(1-0.1)=100*0.9=90\)).

Re: x percent of y percent of z is decreased by y percent. What [#permalink]

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10 Oct 2014, 20:03

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Re: x percent of y percent of z is decreased by y percent. What [#permalink]

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15 Jun 2016, 17:20

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