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If S is the set of the seven smallest prime numbers, and two different
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17 Apr 2022, 23:41
17 Apr 2022, 23:41
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If \(S\) is the set of the seven smallest prime numbers, and two different numbers are randomly selected from \(S\), what is the probability the sum of the two selected numbers is odd?
A) \(\frac{1}{7}\)
B) \(\frac{2}{7}\)
C) \(\frac{11}{42}\)
D) \(\frac{13}{42}\)
E) \(\frac{1}{2}\)
A) \(\frac{1}{7}\)
B) \(\frac{2}{7}\)
C) \(\frac{11}{42}\)
D) \(\frac{13}{42}\)
E) \(\frac{1}{2}\)
Part of the project: Skill Builder Project for a Q170
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GRE Math Essentials for a TOP Quant Score - Q170!!! (2021)
GRE Geometry Formulas for a Q170
GRE - Math Book
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GRE Math Essentials for a TOP Quant Score - Q170!!! (2021)
GRE Geometry Formulas for a Q170
GRE - Math Book
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Re: If S is the set of the seven smallest prime numbers, and two different
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18 Apr 2022, 06:13
18 Apr 2022, 06:13
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Carcass wrote:
If \(S\) is the set of the seven smallest prime numbers, and two different numbers are randomly selected from \(S\), what is the probability the sum of the two selected numbers is odd?
A) \(\frac{1}{7}\)
B) \(\frac{2}{7}\)
C) \(\frac{11}{42}\)
D) \(\frac{13}{42}\)
E) \(\frac{1}{2}\)
A) \(\frac{1}{7}\)
B) \(\frac{2}{7}\)
C) \(\frac{11}{42}\)
D) \(\frac{13}{42}\)
E) \(\frac{1}{2}\)
The seven smallest prime numbers are: 2, 3, 5, 7, 11, 13, 17
Only 1 of those primes is even.
P(sum is odd) = P(1st number is odd AND 2nd number is even OR 1st number is even AND 2nd number is odd)
= [P(1st number is odd) x P(2nd number is even)] + [P(1st number is even) x P(2nd number is odd)]
= [6/7 x 1/6] + [1/7 x 6/6]
= 1/7 + 1/7
= 2/7
Answer: B
gmatclubot
Re: If S is the set of the seven smallest prime numbers, and two different [#permalink]
18 Apr 2022, 06:13
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