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Intern  Joined: 19 Dec 2009
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If k is a positive integer and the tens digit of k+5 is 4, what is the  [#permalink]

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19 00:00

Difficulty:   55% (hard)

Question Stats: 62% (01:48) correct 38% (01:57) wrong based on 816 sessions

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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?

Originally posted by bekbek on 06 Jan 2010, 22:18.
Last edited by Bunuel on 27 Jul 2015, 08:48, edited 1 time in total.
Renamed the topic, edited the question and added the OA.
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Re: Ten's digit + 5 (GMATPrep q29)  [#permalink]

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6
11
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.

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Re: Ten's digit + 5 (GMATPrep q29)  [#permalink]

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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,
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.... ##### General Discussion
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Re: If k is a positive integer and the tens digit of k+5 is 4, what is the  [#permalink]

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bekbek wrote:
Could anyone help what the question asks? Thanks.

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.

OA is "B"

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?

yes. That is correct.

k can be any sized integer from 2 digit or more (it has to be at least 2 digits since the stimulus says it has a tens digit)

lets consider that k is 3 digits: abc

From the stimulus, in order for the tens digit of k+5 to equal 4: a35 < k < a45
here we see that the value of a doesn't matter so we only need to consider 2 digit numbers for k.
so 35<k<45.

1) this is redundant from the information in the stimulus. INSUFF.
2) the units digit of k can be greater than 5 only when the tens digit is 3. SUFF.
Manager  Joined: 17 Mar 2010
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Re: Ten's digit + 5 (GMATPrep q29)  [#permalink]

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Question is not telling digit + 5 it is telling number + 5
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Re: Ten's digit + 5 (GMATPrep q29)  [#permalink]

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2
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
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Re: Ten's digit + 5 (GMATPrep q29)  [#permalink]

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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? I solved it this way:

Stmt1:

Now the possible values satisfying this statement and question statement are:
where, nos in bold represtents K.

36+5=41
37+5=42
38+5=43
'
'
'
till 44+5=49

But since there are are two answers for ten's Digit of K ie 3 and 4, stmt 1 is NS.

Now taking stmt2 alone we can say that all the values where K's Ten's digits is 3 qualifies the statement condition, hence it is sufficient alone.All other values with K's Ten's digits as 4 will not qualify because in that case the 2nd stmt condition that K's unit digit is greater than 5 is not met.

Hope it is clear!!!
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Re: Ten's digit + 5 (GMATPrep q29)  [#permalink]

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I had interpreted the question as tenth digit of K when added by 5 gives 4. So tenth digit can be 9.

Did anyone else interpret like this? Confusion is if 5 is added to number or tens digit
Intern  Joined: 23 Jun 2010
Posts: 22
Re: Ten's digit + 5 (GMATPrep q29)  [#permalink]

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udaymathapati wrote:
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,
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.... I agree. The way the question is worded is misleading. Initially even I took it to be the tens digit of a number + 5 = 4 i.e. if a two digit number was say TU then T+5 =4. It made no sense. So I decided that it was one of those badly worded questions and took it to be k + 5 instead of T + 5.
Once I got that correct, the question seemed pretty straight forward from there on... The trap here is that the question doesn't ask for the number k, rather asks what is the tens digit i.e. T. Thus B is sufficient.
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If k is a positive integer and the tens digit of k+5 is 4, what  [#permalink]

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getzgetzu wrote:
If k is a positive integer and 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.

Hi, For me the answer for this DS is E ...... but different guys gave different answers for this, Can Elaborate & discuss, this Pls.
Math Expert V
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Re: If k is a positive integer and the tens digit of k+5 is 4, w  [#permalink]

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manishuol wrote:
getzgetzu wrote:
If k is a positive integer and 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.

Hi, For me the answer for this DS is E ...... but different guys gave different answers for this, Can Elaborate & discuss, this Pls.

The correct answer is B. Check here: if-k-is-a-positive-integer-and-the-tens-digit-of-k-5-is-100041.html#p780539

Hope it helps.
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Re: If k is a positive integer and the tens digit of k+5 is 4  [#permalink]

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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

1) K > 35 . It can be 36,37,.....40,41.....etc.
In case K< 40 than the answer is 3. If K>=40 and K <45 than the answer is 4. Insufficient.

2)Units digit is greater than 5. In this scenario, the integer has to be less than equal to 40. Therefore tens digit is 3. Hence B.
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Re: If k is a positive integer and the tens digit of k+5 is 4, what is the  [#permalink]

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bekbek wrote:
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?

We need to find the tens digit of k.

(1).... k could be any no in range (36 - 44).. Tens digit can be 3 or 4.. Insufficient..

(2).... k can only be (36-39).. Tens digit can be 3 only.. Sufficient..
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Re: If k is a positive integer and the tens digit of k+5 is 4  [#permalink]

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bekbek wrote:
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?

Hi Bekbek, i'm new here. How do you know how to classify whether this questions is 700 level or not? because it seems quite straightforward as compared to the other 700 level questions.
Math Expert V
Joined: 02 Sep 2009
Posts: 59674
Re: If k is a positive integer and the tens digit of k+5 is 4  [#permalink]

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SamuelWitwicky wrote:
bekbek wrote:
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?

Hi Bekbek, i'm new here. How do you know how to classify whether this questions is 700 level or not? because it seems quite straightforward as compared to the other 700 level questions.

The system itself classifies a question based on users attempts shown in stats.
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Re: If k is a positive integer and the tens digit of k+5 is 4  [#permalink]

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Bunuel wrote:
SamuelWitwicky wrote:
bekbek wrote:
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?

Hi Bekbek, i'm new here. How do you know how to classify whether this questions is 700 level or not? because it seems quite straightforward as compared to the other 700 level questions.

The system itself classifies a question based on users attempts shown in stats.

oh wow! ok thanks a lot for answering my questions!
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Re: If k is a positive integer and the tens digit of k+5 is 4  [#permalink]

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saxenashobhit wrote:
I had interpreted the question as tenth digit of K when added by 5 gives 4. So tenth digit can be 9.

Did anyone else interpret like this? Confusion is if 5 is added to number or tens digit

I read the question as same as you , is the wording of the question a trap designed deliberately by the GMAC？
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Re: If k is a positive integer and the tens digit of k+5 is 4  [#permalink]

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Plug in some smart numbers.
1. K could be 39 or 40, both cases you get 4 as the tens digit. So, A,D out.
2. Since units digits of k can only be 6,7,8,9, start with 36. It can't be 40, so K can be 36,37,38,39 and in all these cases adding 5 will give a tens digit 4. B is the answer.
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Re: If k is a positive integer and the tens digit of k+5 is 4  [#permalink]

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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

(1) if k =36, k+5 =41, which satisfies the question stem. so when 35 < k < 44, the tens digit of k+5 will be 4, not sufficient.
(2) The units digit of k can be 6,7, 8 or 9, in this case to make the tens digit of k+5 = 4, the tens digit of k always has to be 3. sufficient. Re: If k is a positive integer and the tens digit of k+5 is 4   [#permalink] 25 Nov 2019, 16:38
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