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If k is a positive integer and the tens digit of k+5 is 4
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Author:  bekbek [ 06 Jan 2010, 21:18 ]
Post subject:  If k is a positive integer and the tens digit of k+5 is 4, what is the

If k is a positive integer and the tens digit of k+5 is 4, what is the tens digit of k?

(1) k > 35
(2) The units digit of k is greater than 5

Does it mean it can be:
36, 37 ... 44. from (1) statement and 36, 37, 38 and 39 from the (2) statement.
and k is 3?

Author:  Bunuel [ 12 Sep 2010, 20:31 ]
Post subject:  Re: Ten's digit + 5 (GMATPrep q29)

If k is a positive integer and the tens digit of k+5 is 4, what is the tens digit of k?

Translate the stem: "the tens digit of k+5 is 4" --> \(40\leq{k+5}\leq{49}\) --> \(35\leq{k}\leq{44}\) --> so the tens digit of \(k\) could be 3 or 4.

Side note: strictly speaking \(k\) could be more than two digit number (for example 3-digit \(x40\leq{k+5}\leq{x49}\) ), though as we are interested only in units and tens digit then this wouldn't change anything and we can neglect other digits.

(1) k > 35 --> just tells us that \(k\neq{35}\), so we have \(35<{k}\leq{44}\) --> the tens digit of \(k\) could still be 3 or 4. Not sufficient.

(2) The units digit of k is greater than 5 --> \(k\) could only be 36, 37, 38, 39 --> so the tens digit of \(k\) is 3. Sufficient.

Answer: B.

Author:  udaymathapati [ 30 Aug 2010, 08:24 ]
Post subject:  Re: Ten's digit + 5 (GMATPrep q29)

alienfluid wrote:
I can't seem to understand the question - how can a digit + 5 = 4? Are we talking about rounding numbers here?

Can someone please explain? :(


Hi,
It's been asked about tens digit of K+5=4 hence its possible to have 4 as answer....
Answer should be B.
My explanation for the answer as follows;
1. K>35
Stmt one satisfies many numbers starting from 36 till 44 where tens digit of k+5 is 4 (E.g. 36+5=41, 37+5=42....41+5=46). Here tens digit of K has two options either 3 or 4 hence can't answer uniqure number K.

2. Unit Digit of K is >5
For this we have only 4 options available which satisfies tens digit of k+5=4 condition. Numbers are 36, 37, 38 and 39. All these 4 numbers have only one unique number as tens digit i.e. 3 Hence we got our answer. Hence B is suff to answer the question.

If you like explanation, consider for kudos.... :-D

Author:  BeavisMan [ 01 Sep 2010, 14:08 ]
Post subject:  Re: Ten's digit + 5 (GMATPrep q29)

Question stem says 40 <= k+5 <= 49, thus 35 <= k <= 44
Statement 1 says k > 35, thus 36 <= k <= 44. Tens digit could be 3 or 4, insufficient
Taking into account the range of k provided in the question stem, statement 2 says that 36 <= k <= 39. Units digit must be 3, sufficient
Answer B

Author:  bumpbot [ 24 Jan 2023, 02:27 ]
Post subject:  Re: If k is a positive integer and the tens digit of k+5 is 4,

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