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The operation & is defined for all integers a and b by the

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The operation & is defined for all integers a and b by the  [#permalink]

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New post 24 Oct 2013, 09:47
4
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A
B
C
D
E

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Question Stats:

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The operation & is defined for all integers a and b by the equation a&b = (a - 1)(b - 1). If x&13 = 96, what is the value of x ?

(A) 7
(B) 8
(C) 9
(D) 10
(E) 12

GH-04.15.13 | OE to follow
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Re: The operation & is defined for all integers a and b by the  [#permalink]

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New post 24 Oct 2013, 09:50
avohden wrote:
The operation & is defined for all integers a and b by the equation a&b = (a - 1)(b - 1). If x&13 = 96, what is the value of x ?

(A) 7
(B) 8
(C) 9
(D) 10
(E) 12

GH-04.15.13 | OE to follow


a&b = (a - 1)(b - 1)
x&13 = (x-1)(13-1) = 96 --> x-1=8 --> x=9.

Answer: C.
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Re: The operation & is defined for all integers a and b by the  [#permalink]

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New post 24 Oct 2013, 09:51
1
Bunuel wrote:
avohden wrote:
The operation & is defined for all integers a and b by the equation a&b = (a - 1)(b - 1). If x&13 = 96, what is the value of x ?

(A) 7
(B) 8
(C) 9
(D) 10
(E) 12

GH-04.15.13 | OE to follow


a&b = (a - 1)(b - 1)
x&13 = (x-1)(13-1) = 96 --> x-1=8 --> x=9.

Answer: C.


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Hope it helps.
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Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


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Senior Manager
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User avatar
Status: 1,750 Q's attempted and counting
Affiliations: University of Florida
Joined: 09 Jul 2013
Posts: 494
Location: United States (FL)
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GMAT 1: 600 Q45 V29
GMAT 2: 590 Q35 V35
GMAT 3: 570 Q42 V28
GMAT 4: 610 Q44 V30
GPA: 3.45
WE: Accounting (Accounting)
Re: The operation & is defined for all integers a and b by the  [#permalink]

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New post 29 Oct 2013, 21:00
Official Explanation

Answer: C
If a&b = (a - 1)(b - 1), we can come up with an algebraic representation of x&13:

x&13 = (x - 1)(13 -1), or: (x - 1)(12)

We know that's equal to 96, so we can solve for x: 96 = (x-1)(12) | 8 = x - 1 | x = 9, choice (C).
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Re: The operation & is defined for all integers a and b by the  [#permalink]

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Re: The operation & is defined for all integers a and b by the &nbs [#permalink] 22 Dec 2018, 14:37
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