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M13-29

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M13-29  [#permalink]

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New post 16 Sep 2014, 00:50
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

96% (00:33) correct 4% (00:00) wrong based on 23 sessions

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What was Silvia's income in December?


(1) Silvia's income in December was $50 more than her average monthly income during the year.

(2) Silvia's income in December was twice her average monthly income during the year.

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Re M13-29  [#permalink]

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New post 16 Sep 2014, 00:50
Official Solution:


(1) Silvia's income in December was $50 more than her average monthly income during the year. Given: \(December=Average+$50\). Not sufficient.

(2) Silvia's income in December was twice her average monthly income during the year. Given: \(December=2*Average\). Not sufficient.

(1)+(2) We have two distinct linear equations with two variables, hence we can solve it. Sufficient.


Answer: C
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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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Re: M13-29  [#permalink]

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New post 23 Sep 2018, 23:33
This is probably a silly approach. But taking #1, can't you go:

For total income during the year, T = 12x where is the original average.

But with #1, T=11x+50

Solving the two simultaneously, T=50 and hence D=50+50 = 100.

Would love to know where the flaw is in my approach. I am sure I am doing something silly.
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Re: M13-29 &nbs [#permalink] 23 Sep 2018, 23:33
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