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

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VP
Joined: 31 Oct 2013
Posts: 1162
Concentration: Accounting, Finance
GPA: 3.68
WE: Analyst (Accounting)
The positive quantities x,y and z vary over time, and 2x/3 always equa  [#permalink]

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08 Feb 2019, 14:07
1
00:00

Difficulty:

45% (medium)

Question Stats:

53% (01:37) correct 47% (02:02) wrong based on 19 sessions

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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%
Director
Joined: 18 Jul 2018
Posts: 679
Location: India
Concentration: Finance, Marketing
WE: Engineering (Energy and Utilities)
Re: The positive quantities x,y and z vary over time, and 2x/3 always equa  [#permalink]

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08 Feb 2019, 20:01
1
2x/3 = 16yz
x = 24yz

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

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

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VP
Joined: 09 Mar 2018
Posts: 1002
Location: India
Re: The positive quantities x,y and z vary over time, and 2x/3 always equa  [#permalink]

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08 Feb 2019, 20:22
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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Manager
Joined: 12 Sep 2017
Posts: 141
The positive quantities x,y and z vary over time, and 2x/3 always equa  [#permalink]

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13 Feb 2019, 15:05
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

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
The positive quantities x,y and z vary over time, and 2x/3 always equa   [#permalink] 13 Feb 2019, 15:05
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