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Manager  Joined: 18 Feb 2015
Posts: 81
If the unit digit of the positive integer n is  [#permalink]

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8 00:00

Difficulty:   25% (medium)

Question Stats: 76% (01:28) correct 24% (01:49) wrong based on 210 sessions

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If the unit digit of the positive integer n is 5, what is the tens digit of n?

(1) The tens digit of n+5 is 7.
(2) The tens digit of n-6 is 5.
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Joined: 06 May 2015
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Re: If the unit digit of the positive integer n is  [#permalink]

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2
it is given that unit digit is 5 so No. can be 5, 15, 65,75or 85 .i.e anything that unit digit is 5
1st stmt- N+5=tenth digit is 7
so only two digit integer if n=65 +5=70 ( tenth digit is 7) while 75+5=80
so it confirm that 65 is that No.
2nd Stmt If 6 is reduced from N that tenth digit will be 5 here also 65-6=59( tenth digit is 5)

so its D
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If the unit digit of the positive integer n is  [#permalink]

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shravan2025 wrote:
it is given that unit digit is 5 so No. can be 5, 15, 65,75or 85 .i.e anything that unit digit is 5
1st stmt- N+5=tenth digit is 7
so only two digit integer if n=65 +5=70 ( tenth digit is 7) while 75+5=80
so it confirm that 65 is that No.
2nd Stmt If 6 is reduced from N that tenth digit will be 5 here also 65-6=59( tenth digit is 5)

so its D

Good one...Tried in the same way..

Here the number is 65 and its tens digits is 6 and units 5..... In GMAT if stat 1 and stat 2 individually sufficient means ..we get same result from both.
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Re: If the unit digit of the positive integer n is  [#permalink]

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1
2
There is 1 variable (the tens digit of n) in the original condition. In order to match the number of variables and the number of equations, we need 1 equation. Since con 1) and con 2) each has 1 equation, there is a high chance that D is the correct answer.
In case of con 1), the tens digit is always 6. The answer is unique and the condition is sufficient.
In case of con 2), the tens digit is always 6 as well. The answer is unique and the condition is sufficient. Hence, the correct answer is D.
Attachments variable approach's answer probability.jpg [ 219.74 KiB | Viewed 5929 times ]

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Re: If the unit digit of the positive integer n is  [#permalink]

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HarveyKlaus wrote:
If the unit digit of the positive integer n is 5, what is the tens digit of n?

(1) The tens digit of n+5 is 7.
(2) The tens digit of n-6 is 5.

let the tens digit be t

From (1)

t5
+ 5
----
70 => only value for t is 6

From (2)

t5
- 6
----
59 => only value for t is 6

Therefore D
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Re: If the unit digit of the positive integer n is  [#permalink]

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Top Contributor
HarveyKlaus wrote:
If the unit digit of the positive integer n is 5, what is the tens digit of n?

(1) The tens digit of n+5 is 7.
(2) The tens digit of n-6 is 5.

(1)The tens digit of n+5 is 7;value of n ranged from 65 to 72,Since unit digit is 5,thus n=65,so tens digit of n=6,Sufficient

(2) The tens digit of n-6 is 5;value of n ranged from 56 to 65,Since unit digit is 5,thus n=65,so tens digit of n=6,Sufficient

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Re: If the unit digit of the positive integer n is  [#permalink]

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_________________ Re: If the unit digit of the positive integer n is   [#permalink] 23 Nov 2019, 01:30
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# If the unit digit of the positive integer n is  