When the positive integer x is divided by 9, the remainder is 5. What is the remainder when 3x is divided by 9?
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When the positive integer x is divided by 9
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VP_Jim
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Try plugging in a number for X.
Let's say X=14 (we have to pick a number that, when it is divided by 9, the remainder is 5). Now we have have to figure out what the remainder is when 14*3=42 is divided by 9. 42/9 leaves a remainder of 6.
Let's say X=14 (we have to pick a number that, when it is divided by 9, the remainder is 5). Now we have have to figure out what the remainder is when 14*3=42 is divided by 9. 42/9 leaves a remainder of 6.
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Ian Stewart
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If you are going to choose a value for x here- not a bad approach for this question- I'd merely add that the smaller the value you choose for x, the faster the work. In this question, you could let x = 5 (when you divide 5 by 9, the quotient is zero and the remainder is 5). Then 3x = 15, and the remainder is 6.
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minkathebest
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I am trying to figure out why this approach is incorrect:
If x=14 for this question:
x/9 , remainder = 4
3x/9, if I simplify FIRST, I get x/3 and then plugin, 14/3, remainder is 2 and TWO is not an answer choice.
What am I doing wrong here?
If x=14 for this question:
x/9 , remainder = 4
3x/9, if I simplify FIRST, I get x/3 and then plugin, 14/3, remainder is 2 and TWO is not an answer choice.
What am I doing wrong here?
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GMATGuruNY
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You determined the remainder when x is divided by 3:minkathebest wrote:I am trying to figure out why this approach is incorrect:
If x=14 for this question:
x/9 , remainder = 4
3x/9, if I simplify FIRST, I get x/3 and then plugin, 14/3, remainder is 2 and TWO is not an answer choice.
What am I doing wrong here?
R=2.
The question stem asks for the remainder when 3x is divided by 9.
Since the two values being divided (3x and 9) are 3 times as great as the values that you used (x and 3), the remainder also will be 3 times as great:
3*2 = 6.
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I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
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