#1
1st March 2016, 09:01 AM
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Gcd gmat
hii sir, I am preparing for the GMAT Examination will you please give me some sample question with Solution to the GCD Maths questions ?
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#2
1st March 2016, 10:11 AM
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Re: Gcd gmat
As you asking for the GCD Questions of the GMAT Examination the GCD Questions of the GMAT Examination are as follow: What is the greatest common divisor of positive integers m and n? 1) m is a prime number 2) 2n = 7m What is the greatest common divisor of positive integers m and n? 1) m is a prime number 2) 2n = 7m Solution : Statement 1: m is a prime number If m is a prime number, it has exactly 2 divisors (1 and m), so this tells us that the GCD of m and n must be either 1 or m. Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT. Statement 2: 2n = 7m If 2n = 7m then we can rearrange the equation to get n = (7/2)m Notice that if m were to equal an ODD number, then n would not be an integer. For example, if m = 3, then n = 21/2 (n is not an integer). Similarly, if m = 11, then n = 77/2 (n is not an integer). So, in order for n to be an INTEGER, m must be EVEN. If m must be EVEN, there are several possible values for m and n. Consider these two cases: case a: m = 2 and n = 7, in which case the GCD = 1 case b: m = 4 and n = 14, in which case the GCD=2 Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT. Statements 1 & 2 combined From statement 1, we know that m is prime, and from statement 2, we know that m is even. Since 2 is the only even prime number, we can conclude that m must equal 2. If m = 2, then n must equal 7, which means that the GCD must be 1. |