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# M17-10

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Math Expert
Joined: 02 Sep 2009
Posts: 46284

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16 Sep 2014, 01:01
1
1
00:00

Difficulty:

45% (medium)

Question Stats:

62% (00:37) correct 38% (01:01) wrong based on 94 sessions

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If $$x = 708 * 10^{-8}$$, $$y = 78 * 10^{-7}$$, and $$z = 0.75 * 10^{-6}$$, which of the following is correct?

A. $$x \lt y \lt z$$
B. $$y \lt x \lt z$$
C. $$x \lt z \lt y$$
D. $$z \lt x \lt y$$
E. $$z \lt y \lt x$$

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Math Expert
Joined: 02 Sep 2009
Posts: 46284

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16 Sep 2014, 01:01
Official Solution:

If $$x = 708 * 10^{-8}$$, $$y = 78 * 10^{-7}$$, and $$z = 0.75 * 10^{-6}$$, which of the following is correct?

A. $$x \lt y \lt z$$
B. $$y \lt x \lt z$$
C. $$x \lt z \lt y$$
D. $$z \lt x \lt y$$
E. $$z \lt y \lt x$$

$$z = 0.75 * 10^{-6} = 75 * 10^{-8} \lt x = 708 * 10^{-8} \lt y = 780 * 10^{-8}$$.

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Intern
Joined: 12 Aug 2014
Posts: 3

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19 Oct 2015, 22:48
Can someone please clarify this question, I had it as: z < y< x

what am I missing?
Intern
Joined: 14 Oct 2015
Posts: 36
GMAT 1: 640 Q45 V33

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05 Nov 2015, 06:50
6side wrote:
Can someone please clarify this question, I had it as: z < y< x

what am I missing?

Agree the explanation could be expanded. Find a common denominator, I suggest 10^6. X = 7.08, Y = 7.8, Z = 0.75; I think we all agree that 0.75 < 7.08 < 7.8 OR Z < X < Y
Manager
Joined: 28 Dec 2016
Posts: 88
Location: United States (IL)
Concentration: Marketing, General Management
Schools: Johnson '20 (M)
GMAT 1: 700 Q47 V38

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22 Jan 2017, 12:32
3
One of the easy ways to solve this is to multiply x,y, and z by 10^8.
We can solve it under 20 seconds then.

Therefore we have:

x= 708 (10^-8)(10^8) = 708(10^0) = 708(1) = 708
y =78 (10^-7)(10^8) = 78(10^1) = 78(10) = 780
z = 0.75 (10^-6)(10^8) = 0.75(10^2) = 0.75(100) = 75

it is evident then, z<x<y.

Hope it helps.
BSchool Forum Moderator
Joined: 07 Jan 2016
Posts: 727
Location: India
GMAT 1: 710 Q49 V36

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25 Apr 2017, 02:01
x= 70.8 * 10^ -7
y = 78 * 10^-7
z= 7.5 * 10^-7

when powers are same we can compare the values associated with the power and we can see

option D fits

z<x<y
Re: M17-10   [#permalink] 25 Apr 2017, 02:01
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# M17-10

Moderators: chetan2u, Bunuel

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