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# D01-42

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Senior Manager
Status: Some status
Joined: 28 Jun 2012
Posts: 331
Location: Albania
GMAT 4: 660 Q51 V49
GRE 1: 336 Q165 V166
GPA: 3.16
WE: Project Management (Health Care)

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22 Dec 2014, 08:10
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KUDOS
If x is an integer and $$9 \lt x^2 \lt 99$$, then what is the value of maximum possible value of $$x$$ minus minimum possible value of $$x$$?

A. $$5$$
B. $$6$$
C. $$7$$
D. $$18$$
E. $$20$$
Senior Manager
Status: Some status
Joined: 28 Jun 2012
Posts: 331
Location: Albania
GMAT 4: 660 Q51 V49
GRE 1: 336 Q165 V166
GPA: 3.16
WE: Project Management (Health Care)

### Show Tags

22 Dec 2014, 08:10
Official Solution:

If x is an integer and $$9 \lt x^2 \lt 99$$, then what is the value of maximum possible value of $$x$$ minus minimum possible value of $$x$$?

A. $$5$$
B. $$6$$
C. $$7$$
D. $$18$$
E. $$20$$

Notice that $$x$$ can take positive, as well as negative values to satisfy $$9 \lt x^2 \lt 99$$, hence $$x$$ can be: -9, -8, -7, -6, -4, 4, 5, 6, 7, 8, or 9. We are asked to find the value of x(max)-x(min), and since x(max)=9 and x(min)=-9 then x(max)-x(min)=9-(-9)=18.

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Joined: 14 Nov 2016
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Location: Malaysia

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21 Feb 2017, 19:43
mpmbtr wrote:
Official Solution:

If x is an integer and $$9 \lt x^2 \lt 99$$, then what is the value of maximum possible value of $$x$$ minus minimum possible value of $$x$$?

A. $$5$$
B. $$6$$
C. $$7$$
D. $$18$$
E. $$20$$

Notice that $$x$$ can take positive, as well as negative values to satisfy $$9 \lt x^2 \lt 99$$, hence $$x$$ can be: -9, -8, -7, -6, -4, 4, 5, 6, 7, 8, or 9.
We are asked to find the value of $$x(max)-x(min)$$, and since $$x(max)=9$$ and $$x(min)=-9$$ then $$x(max)-x(min)=9-(-9)=18$$.

Dear Bunuel, Shall we consider x instead of $$x^2$$ in the official solution?

$$9<x^2<99$$

$$\sqrt{9}<x<\sqrt{99}$$

$$\sqrt{9}<x<\sqrt{100}$$

$$3<x<10$$

$$-3<x<-10$$
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D01-42   [#permalink] 21 Feb 2017, 19:43
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# D01-42

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