If 2-digit positive integer n is 12 times of the tens digit of n, what is the value of n?
1) The tens digit of n is 3.
2) The sum of the tens digit and the units digit of n is 9.
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If 2-digit positive integer n is 12 times of the tens digit
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Max@Math Revolution
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Max@Math Revolution
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There are 3 variables (n, a, b) and 1 equation (10a+b=12a) in the original condition. Since we need 1 more equation, the correct answer is D.
- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
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Brent@GMATPrepNow
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Target question: What is the value of n?Max@Math Revolution wrote:If 2-digit positive integer n is 12 times the tens digit of n, what is the value of n?
1) The tens digit of n is 3.
2) The sum of the tens digit and the units digit of n is 9.
Given: 2-digit positive integer n is 12 times the tens digit of n
Let's see what 2-digit integers meet this condition.
Case a: If the tens digit of n is 1, then n could be 12
Case b: If the tens digit of n is 2, then n could be 24
Case c: If the tens digit of n is 3, then n could be 36
Case d: If the tens digit of n is 4, then n could be 48
That's it! There are no other possible values of n.
So, n must be one of these four values.
No onto the statements...
Statement 1: The tens digit of n is 3
When we check our 4 possible cases, we see that case c (n = 36) is the only one that meets the information provided in statement 1.
So, n MUST equal 36
Since we can answer the target question with certainty, statement 1 is SUFFICIENT
Statement 2: The sum of the tens digit and the units digit of n is 9.
When we check our 4 possible cases, we see that case c (n = 36) is the only one that meets the information provided in statement 1.
So, n MUST equal 36
Since we can answer the target question with certainty, statement 2 is SUFFICIENT
Answer = D
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
