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In the number 1.4ab5, a and b represent single positive
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Updated on: 11 Jul 2013, 09:14
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In the number 1.4ab5, a and b represent single positive digits. If x = 1.4ab5, what is the value of 10 – x? (1) If x is rounded to the nearest hundredth, then 10 – x = 8.56. (2) If x is rounded to the nearest thousandth, then 10 – x = 8.564.
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Originally posted by shinewine on 28 Aug 2006, 15:12.
Last edited by Bunuel on 11 Jul 2013, 09:14, edited 1 time in total.
Edited the question and added the OA




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In the number 1.4ab5, a and b represent single positive
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11 Jul 2013, 09:42
fozzzy wrote: What's the OA for this question? In the number 1.4ab5, a and b represent single positive digits. If x = 1.4ab5, what is the value of 10 – x?Given: \(x = 1.4ab5\). Notice that we need to find the values of a and b. (1) If x is rounded to the nearest hundredth, then 10 – x = 8.56 > x rounded to the nearest hundredth is 1.44, which implies that \(a\) can be 3 if \(b\geq{5}\) or 4 if \(b<{5}\). Not sufficient. (2) If x is rounded to the nearest thousandth, then 10 – x = 8.564 > x rounded to the nearest thousandth is 1.436. So, \(a=3\) and \(b=5\) (since the tenthousandths digit is 5, then thousandths digit is rounded up, thus b is 1 less than 6, so 5). Sufficient. Answer: B. Rounding rulesRounding is simplifying a number to a certain place value. To round the decimal drop the extra decimal places, and if the first dropped digit is 5 or greater, round up the last digit that you keep. If the first dropped digit is 4 or smaller, round down (keep the same) the last digit that you keep.Example: 5.3485 rounded to the nearest tenth = 5.3, since the dropped 4 is less than 5. 5.3485 rounded to the nearest hundredth = 5.35, since the dropped 8 is greater than 5. 5.3485 rounded to the nearest thousandth = 5.349, since the dropped 5 is equal to 5. Place ValuesHope it helps. Attachment:
Place Values.png [ 38.87 KiB  Viewed 11941 times ]
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It is B.
A gives 1.44. So x can be 1.4395 or 1.4415  INSUFF
B gives 1.436. So x will be 1.43b5. Since, x is rounded to thousandth place then b has to be 5 in order to get x as 1.436. Thus, x is 1.4355.  SUFF
hence B.



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gmatcrook wrote: It is B.
A gives 1.44. So x can be 1.4395 or 1.4415  INSUFF
B gives 1.436. So x will be 1.43b5. Since, x is rounded to thousandth place then b has to be 5 in order to get x as 1.436. Thus, x is 1.4355.  SUFF
hence B.
i am getting 2 answers for statement B>
we can get 1.436 under 2 circumstances
1> when b=6
This is because according to teh rules of rounding of.. if 5 is preceded by an even no.,we don't have to increment ..
2> whn b=5.. but when 5 is preceded by an odd no. , we need to increment.
used this link to understand rounding off..
http://academic.brooklyn.cuny.edu/geolo ... ndoff.html
Please corect me..
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B for me
From 1:
x = 1.44
a could be 3 or 4 depending on b, also b is unknown...insuff
From 2:
x = 1.436 after rounding. clearly a is 3. b is 5 since after rounding it became 6.. we know both a and b...suff



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GMATT73 wrote: (B) has to be it: 1.4355
i am getting 2 answers for statement B>
we can get 1.436 under 2 circumstances
1> when b=6
This is because according to teh rules of rounding of.. if 5 is preceded by an even no.,we don't have to increment ..
2> whn b=5.. but when 5 is preceded by an odd no. , we need to increment.
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Re: In the number 1.4ab5, a and b represent single positive
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11 Jul 2013, 07:38
What's the OA for this question?



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Re: In the number 1.4ab5, a and b represent single positive
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04 Nov 2015, 11:19
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. In the number 1.4ab5, a and b represent single positive digits. If x = 1.4ab5, what is the value of 10 – x? (1) If x is rounded to the nearest hundredth, then 10 – x = 8.56. (2) If x is rounded to the nearest thousandth, then 10 – x = 8.564. In the original condition there are 3 variables (x,a,b) and one equation (x=1.4ab5); 2 more equations are given from the conditions, so there is high chance (C) will be our answer. If we look at the conditions together, BY 1) 101.4ab5=8.56, BY 2) 101.4ab5=8.564, we get a=3, b=6, and the answer becomes (C). But this is a commonly made mistake; if we look at them separately, for condition 1, it is insufficient as x=1.4365, 1.4375 for condition 2, x=1.4365. This is sufficient, and the answer becomes (B). For cases where we need 2 more equation, such as original conditions with “2 variables”, or “3 variables and 1 equation”, or “4 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 70% chance that C is the answer, while E has 25% chance. These two are the majority. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since C is most likely to be the answer using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, D or E.
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Re: In the number 1.4ab5, a and b represent single positive
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26 Apr 2016, 02:47
Why not Option (D).
From each option dont we get 10  X ?
It is already mentioned in both points that if X is .... 10x is ...



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Re: In the number 1.4ab5, a and b represent single positive
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26 Apr 2016, 03:01
somtsat99 wrote: Why not Option (D).
From each option dont we get 10  X ?
It is already mentioned in both points that if X is .... 10x is ... We need to find the value of 10  x, so basically the value of x. (1) says that IF x is rounded to the nearest hundredth, then 10 – x = 8.56, which implies that x rounded to the nearest hundredth is 1.44, not x itself. Please reread the solutions above.
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Re: In the number 1.4ab5, a and b represent single positive
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18 Apr 2017, 17:01
shinewine wrote: In the number 1.4ab5, a and b represent single positive digits. If x = 1.4ab5, what is the value of 10 – x?
(1) If x is rounded to the nearest hundredth, then 10 – x = 8.56. (2) If x is rounded to the nearest thousandth, then 10 – x = 8.564. Target question: What is the value of 10  x?Given: X = 1.4 ab5 Statement 1: If x is rounded to the nearest hundredth, then 10 – x = 8.5610  1.44 = 8.56 So, x rounded to the nearest HUNDREDTH = 1.44 So, x COULD equal 1.4 355, 1.4 365, 1.4 375, 1.4 385, 1.4 395, 1.4 405, 1.4 415, 1.4 425, 1.4 435 OR 1.4 445 Given all of the different possible values of x, 10  x could have MANY different values. Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT Statement 2: If x is rounded to the nearest thousandth, then 10  x = 8.564 10  1.436 = 8.564 In other words, x rounded to the nearest THOUSANDTH = 1.436 This tells us that a must equal 3, leaving us with 1.4 3b5 If 1.4 3b5 rounded to the nearest THOUSANDTH = 1.436, then b MUST equal 5So, x must equal 1.4355, which means 10  x MUST equal 8.5645Since we can answer the target question with certainty, statement 2 is SUFFICIENT Answer: Cheers, Brent
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Re: In the number 1.4ab5, a and b represent single positive
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21 Dec 2018, 21:43
Statement 1. If x is rounded to nearest hundredth digit, then 10 – x = 8.56 i.e. x = 1.44 This is possible for (a , b) = (3, >5) and (4 , <5). Hence, Insufficient. Statement 2. If x is rounded to nearest thousandth digit, 10 – x= 8.564 i.e. x = 1.436 This is only possible when a = 3 and b = 5. Hence, Sufficient.




Re: In the number 1.4ab5, a and b represent single positive
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21 Dec 2018, 21:43






