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If Set A is made up of all 2-digit primes that are one less than a pow
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01 Apr 2022, 02:19
01 Apr 2022, 02:19
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If Set A is made up of all 2-digit primes that are one less than a power of 2, what is the standard deviation of set A?
A. 0
B. 15.1
C. 17
D. 20
E. 23.7
A. 0
B. 15.1
C. 17
D. 20
E. 23.7
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Re: If Set A is made up of all 2-digit primes that are one less than a pow
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01 Apr 2022, 05:46
01 Apr 2022, 05:46
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Carcass wrote:
If Set A is made up of all 2-digit primes that are one less than a power of 2, what is the standard deviation of set A?
A. 0
B. 15.1
C. 17
D. 20
E. 23.7
A. 0
B. 15.1
C. 17
D. 20
E. 23.7
Two-digit powers of 2:
2^4 = 16
2^5 = 32
2^6 = 64
Done!
Now subtract 1 from each value:
16 - 1 = 15
32 - 1 = 31
64 - 1 = 63
Among the three outcomes, 31 is the only prime number, which means Set A = {31}
Since the standard deviation of ONE value is always 0, the correct answer is A.
gmatclubot
Re: If Set A is made up of all 2-digit primes that are one less than a pow [#permalink]
01 Apr 2022, 05:46
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