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k is a prime number
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30 Jul 2020, 15:29
30 Jul 2020, 15:29
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Please help me with this GRE math question.
K is a prime number.
Quantity A: the greatest prime factor of 40k.
Quantity B: the greatest prime factor of 39k.
I know the answer is the relationship cannot be determined from the information given.
Could you please help me explain why? Thanks!
K is a prime number.
Quantity A: the greatest prime factor of 40k.
Quantity B: the greatest prime factor of 39k.
I know the answer is the relationship cannot be determined from the information given.
Could you please help me explain why? Thanks!
Re: k is a prime number
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31 Jul 2020, 07:00
31 Jul 2020, 07:00
For 40 the greatest prime factor is 5 while for 39 it is 13...but k is also a prime number which can be a number less or greater than 13. In the former case the quantities will vary (B>A) and in the latter the quantities will be equal.Also, A = B if k = 13.
Re: k is a prime number
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03 Aug 2020, 04:05
03 Aug 2020, 04:05
40k=40*k=2*2*2*5*k
So the largest prime factor of 40k is either 5 or k
39k=39*k=3*13*k
So the largest prime factor of 39k is either 13 or k
If k= 17, Quantity A= Quantity B
Choice C
If k= 5, Quantity A=5 and Quantity B=13
Choice B
Final Answer: Choice D
So the largest prime factor of 40k is either 5 or k
39k=39*k=3*13*k
So the largest prime factor of 39k is either 13 or k
If k= 17, Quantity A= Quantity B
Choice C
If k= 5, Quantity A=5 and Quantity B=13
Choice B
Final Answer: Choice D
