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The positive quantities x,y and z vary over time, and 2x/3 always equa

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The positive quantities x,y and z vary over time, and 2x/3 always equa  [#permalink]

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New post 08 Feb 2019, 15:07
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The positive quantities x,y and z vary over time, and \(\frac{2x}{3}\) always equals 16yz. If y is tripled and z is halved, then x is

A) decreased by 50%
B)decreased by 33.33%
C)Unchanged
D)Increased by 33.33%
E)increased by 50%
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Re: The positive quantities x,y and z vary over time, and 2x/3 always equa  [#permalink]

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New post 08 Feb 2019, 21:01
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2x/3 = 16yz
x = 24yz

New y = 3y and z = 1/2z
New x = 36yz

(36yz-24yz)/24yz = 12/24*100 = 50% Increase

E is the answer.
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Re: The positive quantities x,y and z vary over time, and 2x/3 always equa  [#permalink]

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New post 08 Feb 2019, 21:22
selim wrote:
The positive quantities x,y and z vary over time, and \(\frac{2x}{3}\) always equals 16yz. If y is tripled and z is halved, then x is

A) decreased by 50%
B)decreased by 33.33%
C)Unchanged
D)Increased by 33.33%
E)increased by 50%


2x/3 = 16yz

Initially x = 24yz

After y is tripled and z is halved

x became = 36yz

% Increase = {(36-24)*yz/ 24yz } * 100
= 50 %

E
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The positive quantities x,y and z vary over time, and 2x/3 always equa  [#permalink]

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New post 13 Feb 2019, 16:05
Afc0892 wrote:
2x/3 = 16yz
x = 24yz

New y = 3y and z = 1/2z
New x = 36yz

(36yz-24yz)/24yz = 12/24*100 = 50% Increase

E is the answer.


Hello Afc0892 !

What's wrong with my approach?

\(2/3\) = 66%

\((2x)/3 = 16yz\)

\((2x)/3 = 16(3y)(z/2)\)

\(((2x)/3 = 16(3y)(z/2))*(2/3)\)

\(((4x)/6 = 16(y)(z))\)

\(2/3\) = 66%
\(4/9\) = 44% --- Decrease
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The positive quantities x,y and z vary over time, and 2x/3 always equa   [#permalink] 13 Feb 2019, 16:05
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