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# The highest term in a set is 3SD above the Mean. The lowest term is 4S

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Intern
Joined: 10 Jul 2016
Posts: 49
Location: India
Concentration: Technology, General Management
GMAT 1: 550 Q36 V30
GPA: 3.65
WE: Information Technology (Consulting)
The highest term in a set is 3SD above the Mean. The lowest term is 4S  [#permalink]

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15 Nov 2017, 21:06
00:00

Difficulty:

15% (low)

Question Stats:

76% (01:17) correct 24% (02:10) wrong based on 66 sessions

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The highest term in a set is 3SD above the Mean. The lowest term is 4SD below the mean. If the highest term is 200 and Range is 140, find the Standard Deviation.

A. 20
B. 60
C. 140
D. 200
E. 300

Source: Experts' Global
Math Expert
Joined: 02 Sep 2009
Posts: 50544
Re: The highest term in a set is 3SD above the Mean. The lowest term is 4S  [#permalink]

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15 Nov 2017, 22:03
1
1
Sangeeta2018 wrote:
The highest term in a set is 3SD above the Mean. The lowest term is 4SD below the mean. If the highest term is 200 and Range is 140, find the Standard Deviation.

A. 20
B. 60
C. 140
D. 200
E. 300

Source: Experts' Global

The highest term in a set is 3SD above the Mean: Highest term = Mean +3SD ;

The lowest term is 4SD below the mean: Lowest term = Mean - 4SD;

Subtract 2 from 1:

Highest term - Lowest term = (Mean +3SD) - (Mean - 4SD);

Range = 7SD;

140 = 7SD;

SD = 20.

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Intern
Joined: 25 Jul 2017
Posts: 2
Re: The highest term in a set is 3SD above the Mean. The lowest term is 4S  [#permalink]

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15 Nov 2017, 22:09
Sangeeta2018 wrote:
The highest term in a set is 3SD above the Mean. The lowest term is 4SD below the mean. If the highest term is 200 and Range is 140, find the Standard Deviation.

A. 20
B. 60
C. 140
D. 200
E. 300

Source: Experts' Global

Let mean be denoted as M
Highest term = M + 4SD
Lowest term = M - 3SD

Range = 140, i.e.
M + 4sd - M + 3sd = 140
7sd = 140
sd = 20;

or

M+4sd = 200 .. eq 1
Range = 140 --> 200 - Least number = 140 ==> least number = 60
M - 3sd = 60 .. eq 2

Solve for sd from eq 1 and 2; you will get 7sd = 140 and sd = 20;

Now my doubt is - where is 20 in the answer choices ??? or did I make a mistake
Math Expert
Joined: 02 Sep 2009
Posts: 50544
Re: The highest term in a set is 3SD above the Mean. The lowest term is 4S  [#permalink]

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15 Nov 2017, 22:11
gmathighh wrote:
Sangeeta2018 wrote:
The highest term in a set is 3SD above the Mean. The lowest term is 4SD below the mean. If the highest term is 200 and Range is 140, find the Standard Deviation.

A. 20
B. 60
C. 140
D. 200
E. 300

Source: Experts' Global

Let mean be denoted as M
Highest term = M + 4SD
Lowest term = M - 3SD

Range = 140, i.e.
M + 4sd - M + 3sd = 140
7sd = 140
sd = 20;

or

M+4sd = 200 .. eq 1
Range = 140 --> 200 - Least number = 140 ==> least number = 60
M - 3sd = 60 .. eq 2

Solve for sd from eq 1 and 2; you will get 7sd = 140 and sd = 20;

Now my doubt is - where is 20 in the answer choices ??? or did I make a mistake

The correct answer is A. Check here: https://gmatclub.com/forum/the-highest- ... l#p1962998

P.S. Edited the options in the original post.
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Intern
Joined: 25 Jul 2017
Posts: 2
Re: The highest term in a set is 3SD above the Mean. The lowest term is 4S  [#permalink]

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15 Nov 2017, 22:18
Bunuel wrote:
gmathighh wrote:
Sangeeta2018 wrote:
The highest term in a set is 3SD above the Mean. The lowest term is 4SD below the mean. If the highest term is 200 and Range is 140, find the Standard Deviation.

A. 20
B. 60
C. 140
D. 200
E. 300

Source: Experts' Global

Let mean be denoted as M
Highest term = M + 4SD
Lowest term = M - 3SD

Range = 140, i.e.
M + 4sd - M + 3sd = 140
7sd = 140
sd = 20;

or

M+4sd = 200 .. eq 1
Range = 140 --> 200 - Least number = 140 ==> least number = 60
M - 3sd = 60 .. eq 2

Solve for sd from eq 1 and 2; you will get 7sd = 140 and sd = 20;

Now my doubt is - where is 20 in the answer choices ??? or did I make a mistake

P.S. Edited the options in the original post.

I have checked the link, Bunuel.
Thank you for ackowledging.
Manager
Joined: 03 May 2014
Posts: 161
Location: India
WE: Sales (Mutual Funds and Brokerage)
Re: The highest term in a set is 3SD above the Mean. The lowest term is 4S  [#permalink]

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22 Nov 2017, 05:38
Range=Max value-min value
Range=140
Max value=200
200=140-min or Min Value=60
we are given
Mean+3SD=200
Mean-4SD=60
subtract the above 2 equations
7SD=140 or SD=140/7=20
Re: The highest term in a set is 3SD above the Mean. The lowest term is 4S &nbs [#permalink] 22 Nov 2017, 05:38
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