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Joined: 02 Sep 2009
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Which of the following sets has the standard deviation greater than the standard deviation of set X={19, 17, 15, 13, 11} A={1, 3, 5, 7, 9} B={2, 4, 6, 8, 10} C={1, 1, 3, 5, 7} A. Set A only B. Set B only C. Set C only D. Sets A, B and C E. None of the sets
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Re M0507
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15 Sep 2014, 23:24
Official Solution: Which of the following sets has the standard deviation greater than the standard deviation of set X={19, 17, 15, 13, 11} A={1, 3, 5, 7, 9} B={2, 4, 6, 8, 10} C={1, 1, 3, 5, 7} A. Set A only B. Set B only C. Set C only D. Sets A, B and C E. None of the sets If we add or subtract a constant to each term in a set the standard deviation will not change. Since each set can be obtained by adding some constant to each term of set X (20 for set A, 21 for set B and 12 for set C), the standard deviations of all sets are the same. Answer: E
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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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Bunuel wrote: Official Solution:
Which of the following sets has the standard deviation greater than the standard deviation of set X={19, 17, 15, 13, 11} A={1, 3, 5, 7, 9} B={2, 4, 6, 8, 10} C={1, 1, 3, 5, 7}
A. Set A only B. Set B only C. Set C only D. Sets A, B and C E. None of the sets
If we add or subtract a constant to each term in a set the standard deviation will not change. Since each set can be obtained by adding some constant to each term of set X (20 for set A, 21 for set B and 12 for set C), the standard deviations of all sets are the same.
Answer: E Can someone please explain (Bunuel if you're listening I'd appreciate the clarification) what exactly the logistics behind "adding some constant to each term" means? I presume like this, if Set x is [1, 2, 3, 4, 5] and adding 20 to it you get [21, 22, 23, 24, 25]. but I'm not sure how this relates either to the standard deviation or to why Bunuel chose different numbers for each set "20 for set A, 21 for set B and 12 for set C"
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Re: M0507
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07 May 2016, 18:41
redfield wrote: Bunuel wrote: Official Solution:
Which of the following sets has the standard deviation greater than the standard deviation of set X={19, 17, 15, 13, 11} A={1, 3, 5, 7, 9} B={2, 4, 6, 8, 10} C={1, 1, 3, 5, 7}
A. Set A only B. Set B only C. Set C only D. Sets A, B and C E. None of the sets
If we add or subtract a constant to each term in a set the standard deviation will not change. Since each set can be obtained by adding some constant to each term of set X (20 for set A, 21 for set B and 12 for set C), the standard deviations of all sets are the same.
Answer: E Can someone please explain (Bunuel if you're listening I'd appreciate the clarification) what exactly the logistics behind "adding some constant to each term" means? I presume like this, if Set x is [1, 2, 3, 4, 5] and adding 20 to it you get [21, 22, 23, 24, 25]. but I'm not sure how this relates either to the standard deviation or to why Bunuel chose different numbers for each set "20 for set A, 21 for set B and 12 for set C" ... the addition is being done to the SET in Question stem  set X={19, 17, 15, 13, 11} 1) add 20 to each item of X {19+20, 17+20, 15+20, 13+20, 11+20} {1,3,5,7,9} SAME as A={1, 3, 5, 7, 9} 2) add 21 to each item of X {19+21, 17+21, 15+21, 13+21, 11+21} {2, 4, 6, 8, 10} SAME as B={2, 4, 6, 8, 10} 1) add 12 to each item of X {19+12, 17+12, 15+12, 13+12, 11+12} {1,1,3,5,7} SAME asC={1, 1, 3, 5, 7}
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Re M0507
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26 Nov 2016, 03:54
I think this is a poorquality question and I don't agree with the explanation. There is an error in Set C. The explanation says 19+12=1? How is that possible?



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Re: M0507
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26 Nov 2016, 04:14
saumyasharma wrote: I think this is a poorquality question and I don't agree with the explanation. There is an error in Set C. The explanation says 19+12=1? How is that possible? The question is fine. X = {19, 17, 15, 13, 11} +12 C = {7, 5, 3, 1, 1} (it's the same set as {1, 1, 3, 5, 7} but in different order).
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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: M0507
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05 Feb 2017, 06:20
Empowergmat Rich, Egmat cab you please explain the concept behind this question. How can I solve similar type of questions?
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Bunuel wrote: Which of the following sets has the standard deviation greater than the standard deviation of set X={19, 17, 15, 13, 11} A={1, 3, 5, 7, 9} B={2, 4, 6, 8, 10} C={1, 1, 3, 5, 7}
A. Set A only B. Set B only C. Set C only D. Sets A, B and C E. None of the sets Dear Bunuel, Two sets dispersed equally along their mean have equal SD. Is this logic fine to solve this question?










