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20 Sep 2023, 01:30
Kudos
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E
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Difficulty:
35%
(medium)
Question Stats:
61% (00:55) correct
39%
(00:52)
wrong
based on 62
sessions
History
Date
Time
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Not Attempted Yet
What is the standard deviation of the terms in set N?
(1) Every prime number between 20 and 50 appears exactly once in set N.
(2) Every term in set N is greater than 20 and less than 50.
(1) Every prime number between 20 and 50 appears exactly once in set N.
(2) Every term in set N is greater than 20 and less than 50.
Bunuel
Finally a new/ unsolved question
Here's how I would go about it:S1: All primes between 20 and 50 appear once, but we dont know about how many non-primes are appearing, which numbers or how many times they appear. So S1 not sufficient.
S2: So now we know that all numbers are between 20 and 50 but dont know about which numbers appeared and if any repetitions.
Together S1 and S2 still don't help with a fixed set N. Hence we cant find the Standard Deviation. So answer is E.
Cheers
23 Sep 2023, 02:52
Kudos
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This is how I "reasoned" my way through the question
Q: What is the standard deviation of the terms in set N?
(1) Every prime number between 20 and 50 appears exactly once in set N.
The prime numbers between 20 & 50 are: 23, 29, 31, 37, 41, 43, 47. This does not provide sufficient information about the SD in set N. We could have many different variants of set N where there are potentially only consecutive integers, like: [20, 21, 22 ... 50] or we could have the set exactly how it is from the prime numbers: [23, 29, 31, 37, 41, 43, 47] that produces a completely different SD. Since we got 2 different choices eliminate this option
(2) Every term in set N is greater than 20 and less than 50.
Again we could have a consecutive integer set that looks like: [21, 22, 23 ... 49] or we could have a completely random set like [23, 29, 35, 39, 47]. Both produce different SD's, therefore eliminate
1/2) Both statement together do not provide new information to determine a unique value. Hence I chose answer E
Q: What is the standard deviation of the terms in set N?
(1) Every prime number between 20 and 50 appears exactly once in set N.
The prime numbers between 20 & 50 are: 23, 29, 31, 37, 41, 43, 47. This does not provide sufficient information about the SD in set N. We could have many different variants of set N where there are potentially only consecutive integers, like: [20, 21, 22 ... 50] or we could have the set exactly how it is from the prime numbers: [23, 29, 31, 37, 41, 43, 47] that produces a completely different SD. Since we got 2 different choices eliminate this option
(2) Every term in set N is greater than 20 and less than 50.
Again we could have a consecutive integer set that looks like: [21, 22, 23 ... 49] or we could have a completely random set like [23, 29, 35, 39, 47]. Both produce different SD's, therefore eliminate
1/2) Both statement together do not provide new information to determine a unique value. Hence I chose answer E
