V2

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V2

by oquiella » Wed Nov 04, 2015 6:24 am
x is a positive integer less than 20. What is the value of x?

x is the sum of two consecutive integers.
x is the sum of five consecutive integers.

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by akash singhal » Wed Nov 04, 2015 6:33 am
oquiella wrote:x is a positive integer less than 20. What is the value of x?

x is the sum of two consecutive integers.
x is the sum of five consecutive integers.
Is the answer B??
If I am right I will explain the reasoning.

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by DavidG@VeritasPrep » Wed Nov 04, 2015 6:39 am
akash singhal wrote:
oquiella wrote:x is a positive integer less than 20. What is the value of x?

x is the sum of two consecutive integers.
x is the sum of five consecutive integers.
Is the answer B??
If I am right I will explain the reasoning.
Spend a bit more time evaluating the second statement. (Hint: though 'x' is a positive integer, statement 2 does not stipulate that the five consecutive integers that sum to x must all be positive.)
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by manik11 » Wed Nov 04, 2015 6:53 am
Hi oquiella,

You can just brute force your way out of this one.

Statement 1 : x is the sum of two consecutive integers

Scenario A : 3+4 = 7
Scenario B : 4+5 = 9

Two different values of x --> Not Sufficient

Statement 2 : x is the sum of five consecutive integers.

Scenario A : 1+2+3+4+5 = 15
Scenario B : 0+1+2+3+4 = 10

Two different values of x --> Not Sufficient

Statement 1 + Statement 2

Scenario A : 1+2+3+4+5 = 15 also 8+7 = 15 implies x = 15
Scenario B : -1+0+1+2+3 = 5 also 2+3 = 5 implies x = 5

Not Sufficient

Is the OA E?

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by oquiella » Thu Nov 05, 2015 8:05 am
DavidG@VeritasPrep wrote:
akash singhal wrote:
oquiella wrote:x is a positive integer less than 20. What is the value of x?

x is the sum of two consecutive integers.
x is the sum of five consecutive integers.
Is the answer B??
If I am right I will explain the reasoning.
Spend a bit more time evaluating the second statement. (Hint: though 'x' is a positive integer, statement 2 does not stipulate that the five consecutive integers that sum to x must all be positive.)

Please explain

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by DavidG@VeritasPrep » Thu Nov 05, 2015 11:00 am
oquiella wrote:
DavidG@VeritasPrep wrote:
akash singhal wrote:
oquiella wrote:x is a positive integer less than 20. What is the value of x?

x is the sum of two consecutive integers.
x is the sum of five consecutive integers.
Is the answer B??
If I am right I will explain the reasoning.
Spend a bit more time evaluating the second statement. (Hint: though 'x' is a positive integer, statement 2 does not stipulate that the five consecutive integers that sum to x must all be positive.)

Please explain
I suspect that some percentage of test-takers will see statement 2 and think, okay, x could be 1 + 2 + 3 + 4 + 5, or 15. So that's one value. But if x were 2+ 3 +4 +5 + 6, x would be 20, and that would violate the initial condition, so x can't be 20. Therefore x is 15. Sufficient. The problem with this reasoning is that though x needs to positive, the five consecutive numbers that sum to x do not all need to be positive. x could be 0 + 1 + 2 + 3 + 4, or 10. And x could be -1 +0 +1 +2 +3, or 5. So statement 2 is not sufficient when we consider these other scenarios.
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