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GRE Math Challenge #26-S=1 - 1/2 + 1/3 - 1/4 + 1/5
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08 Sep 2014, 01:25
08 Sep 2014, 01:25
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64% (01:16) correct
35% (01:16) wrong based on 53 sessions
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S=1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6 + 1/7 - 1/8 + 1/9 - 1/10
Column A : S
Column B : 1/2
A)The quantity in Column A is greater
B)The quantity in Column B is greater
C)Both are Equal.
D)The relationship cannot be determined from the information given
Column A : S
Column B : 1/2
A)The quantity in Column A is greater
B)The quantity in Column B is greater
C)Both are Equal.
D)The relationship cannot be determined from the information given
Re: GRE Math Challenge #26-S=1 - 1/2 + 1/3 - 1/4 + 1/5
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07 Mar 2018, 00:05
07 Mar 2018, 00:05
1
sandy wrote:
S=1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6 + 1/7 - 1/8 + 1/9 - 1/10
Column A : S
Column B : 1/2
A)The quantity in Column A is greater
B)The quantity in Column B is greater
C)Both are Equal.
D)The relationship cannot be determined from the information given
Column A : S
Column B : 1/2
A)The quantity in Column A is greater
B)The quantity in Column B is greater
C)Both are Equal.
D)The relationship cannot be determined from the information given
In this stem, we are clearly told that S=1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6 + 1/7 - 1/8 + 1/9 - 1/10
as the list says, 1-1/2 =1/2 and the follwings pairs of minus expressions would be >0 then we can instantly know that the result must be > 1/2. Thus, the ans =A
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Re: GRE Math Challenge #26-S=1 - 1/2 + 1/3 - 1/4 + 1/5
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17 Apr 2020, 06:50
17 Apr 2020, 06:50
1
sandy wrote:
S=1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6 + 1/7 - 1/8 + 1/9 - 1/10
Column A : S
Column B : 1/2
A)The quantity in Column A is greater
B)The quantity in Column B is greater
C)Both are Equal.
D)The relationship cannot be determined from the information given
Column A : S
Column B : 1/2
A)The quantity in Column A is greater
B)The quantity in Column B is greater
C)Both are Equal.
D)The relationship cannot be determined from the information given
Given:
Quantity A: 1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6 + 1/7 - 1/8 + 1/9 - 1/10
Quantity B: 1/2
Simplify to get:
Quantity A: 1/2 + 1/3 - 1/4 + 1/5 - 1/6 + 1/7 - 1/8 + 1/9 - 1/10
Quantity B: 1/2
Subtract 1/2 from both quantities to get:
Quantity A: 1/3 - 1/4 + 1/5 - 1/6 + 1/7 - 1/8 + 1/9 - 1/10
Quantity B: 0
Rewrite Quantity A as follows:
Quantity A: (1/3 - 1/4) + (1/5 - 1/6) + (1/7 - 1/8) + (1/9 - 1/10)
Quantity B: 0
Important: No need to perform any calculations here
Since 1/3 > 1/4, we know that 1/3 - 1/4 is some POSITIVE number.
Since 1/5 > 1/6, we know that 1/5 - 1/6 is some POSITIVE number.
Since 1/7 > 1/8, we know that 1/7 - 1/8 is some POSITIVE number.
Since 1/9 > 1/10, we know that 1/9 - 1/10 is some POSITIVE number.
We get:
Quantity A: (some POSITIVE number) + (some POSITIVE number) + (some POSITIVE number) + (some POSITIVE number)
Quantity B: 0
Quantity A is clearly greater that Quantity B
Answer: A
Cheers,
Brent
