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11 Sep 2017, 00:24
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E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
45%
(medium)
Question Stats:
66% (01:52) correct
34%
(02:14)
wrong
based on 107
sessions
History
Date
Time
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Not Attempted Yet
Is the value of \(\frac{27^a}{6^b}\) a prime number?
(1) 3a – b = 1
(2) b is an integer.
(1) 3a – b = 1
(2) b is an integer.
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
11 Sep 2017, 01:25
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The question reduces to is 3^(3a-b)/2^b a prime number ??
Statement 1: if b=0 then yes it is a prime number . If b=1 or 2 or 3 or any number , then no.
So insufficient.
Statement 2: not sufficient.
Combined not sufficient. If b=0 then yes it is prime and if b= some other integer then , no.
So answer is E.
Sent from my Lenovo TAB S8-50LC using GMAT Club Forum mobile app
Statement 1: if b=0 then yes it is a prime number . If b=1 or 2 or 3 or any number , then no.
So insufficient.
Statement 2: not sufficient.
Combined not sufficient. If b=0 then yes it is prime and if b= some other integer then , no.
So answer is E.
Sent from my Lenovo TAB S8-50LC using GMAT Club Forum mobile app
11 Sep 2017, 03:34
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Find: \(\frac{27^a}{6^b}\) = prime number?
\(\frac{27^a}{6^b}\)
=> \(\frac{3^(3a)}{2^b * 3^b}\)
=> \(\frac{3^(3a-b)}{2^b}\)
Above number can have only 1 prime value = 3
and for it 3a-b=1 and b=0 is the condition
(1) 3a – b = 1
We don't know anything above b . so we dont know anything about the denominator
Not sufficient
(2) b is an integer.
Here we dont know value of a. and here b can take any value 0,1,2...
Not sufficient
1+2
We get one condition to form prime number ie. 3a-b=1, but we don't know anything about b.
b is an integer.. if b=0 than given number is prime number
if b is any other integer than not a prime number.
Answer: E
\(\frac{27^a}{6^b}\)
=> \(\frac{3^(3a)}{2^b * 3^b}\)
=> \(\frac{3^(3a-b)}{2^b}\)
Above number can have only 1 prime value = 3
and for it 3a-b=1 and b=0 is the condition
(1) 3a – b = 1
We don't know anything above b . so we dont know anything about the denominator
Not sufficient
(2) b is an integer.
Here we dont know value of a. and here b can take any value 0,1,2...
Not sufficient
1+2
We get one condition to form prime number ie. 3a-b=1, but we don't know anything about b.
b is an integer.. if b=0 than given number is prime number
if b is any other integer than not a prime number.
Answer: E
