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11 Apr 2018, 21:23
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A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
81% (00:49) correct
19%
(01:07)
wrong
based on 210
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Is the standard deviation of Set A greater than or equal to the standard deviation of Set B?
(1) Set B can be formed by dividing each value in Set A by 4.
(2) Set A consists of 7 unique numbers.
(1) Set B can be formed by dividing each value in Set A by 4.
(2) Set A consists of 7 unique numbers.
12 Apr 2018, 06:06
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Bunuel
Question : Is Standard Deviation of A > Standard deviation of B?
Statement 1: Set B can be formed by dividing each value in Set A by 4.
Since each value of A is divided by 4 to obtain each value of Set B therefore the gaps among the values will also be divided by 4 hence standard deviation will decrease hence
Standard Deviation of A > Standard deviation of B
SUFFICIENT
Statement 2: Set A consists of 7 unique numbers
No Information of Set B hence
NOT SUFFICIENT
Answer: option A
CONCEPT TABLE ON STANDARD DEVIATION
STANDARD DEVIATION
Standard Deviation : Average Deviation of Terms of a set from the Mean value of the Set
1) If we had assumed that all barrels had the same amount of mixture then standard deviation would have been zero. Non Zero standard deviation means that all barrels don't have the same amount of Mixture and the the size of Barrels doesn't matter, all that matters is the amount of Mixture in the barrels
2) The standard deviation of a set doesn't change if a constant is added to/subtracted from each terms of the set
e.g.{1, 2, 3, 4, 5} will have same standard Deviation as {1+10, 2+10, 3+10, 4+10, 5+10}
Reason: The deviation remains same as before if the constant is added to/Subtracted from each term
3) Standard Deviation of the Set changes when a constant term which is not equal to 1 is multiplied with/divides every terms of the set
e.g. {0.7, 1.4, 2.1, 2.8, 3.5} will have Standard Deviation = 0.7* Standard deviation of set {1, 2, 3, 4, 5}
Reason: The deviation gets multiplied by or divided by the same constant that every terms is multiplied or divided with
12 Apr 2018, 07:51
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IMO A
St1 implies that sd in b will decrease compared to A as every term is divided by 4
St2 can't say anything about sd
St1 implies that sd in b will decrease compared to A as every term is divided by 4
St2 can't say anything about sd
