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# a and b are the digits of a two- digit number ab, and b = a

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Moderator
Joined: 18 Apr 2015
Posts: 5909
Followers: 96

Kudos [?]: 1156 [0], given: 5484

a and b are the digits of a two- digit number ab, and b = a [#permalink]  14 Apr 2018, 02:24
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Question Stats:

53% (00:54) correct 46% (01:09) wrong based on 30 sessions
a and b are the digits of a two- digit number ab, and b = a + 3.

 Quantity A Quantity B The positive two-digit number $$ab$$ The positive two-digit number $$ba$$

A. The quantity in Column A is greater
B. The quantity in Column B is greater
C. The two quantities are equal
D. The relationship cannot be determined from the information given
[Reveal] Spoiler: OA

_________________
Director
Joined: 07 Jan 2018
Posts: 604
Followers: 7

Kudos [?]: 546 [1] , given: 88

Re: a and b are the digits of a two- digit number ab, and b = a [#permalink]  15 Apr 2018, 00:24
1
KUDOS
Given that $$ab$$ is a two digit number $$a$$ cannot be $$0$$ since $$0b = b$$

so probable values for $$a =1,2,3,4,5,6$$
$$a$$ cannot also be more than $$6$$ since a is an integer and adding $$3$$ to $$7$$ or more will make b a two digit number in itself which is not possible
for every given value of $$a$$ in the list in order, $$b = 4,5,6,7,8,9$$

so $$ab = 14,25,36,47,58,69$$
hence, $$ba = 41,52,63,74,85,96$$

comparing $$ab$$ to $$ba$$ according to the respective $$1st-6th$$ term above
B>A
_________________

This is my response to the question and may be incorrect. Feel free to rectify any mistakes

Intern
Joined: 05 Jun 2017
Posts: 8
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Kudos [?]: 8 [1] , given: 0

Re: a and b are the digits of a two- digit number ab, and b = a [#permalink]  23 Apr 2018, 14:13
1
KUDOS
Side A:
we are given b = a + 3
ab can be written as
10*a + b
=10a + a + 3
11a + 3

Side B:
ba can be written as
10b + a
= 10(a+3) + a
= 11a + 30

Therefore Side B is greater
Re: a and b are the digits of a two- digit number ab, and b = a   [#permalink] 23 Apr 2018, 14:13
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