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mgmat-integers

by pradeepkaushal9518 » Fri Jul 16, 2010 3:25 am
A.........B........C.........D

The integers A, B, C, and D shown on the number line above are all equally spaced. If C and D are equal to 512 and 513,
respectively, what is the value of A?

511
510
-512
(-7)512
(-12)513

i have choosen B
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by kmittal82 » Fri Jul 16, 2010 3:44 am
Looks correct.

The points are equidistant, and the difference between C and D is 1, hence working backwards from C, B is 511 and A is 510.

Whats the OA?
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by kvcpk » Fri Jul 16, 2010 3:50 am
pradeepkaushal9518 wrote:A.........B........C.........D

The integers A, B, C, and D shown on the number line above are all equally spaced. If C and D are equal to 512 and 513,
respectively, what is the value of A?

511
510
-512
(-7)512
(-12)513

i have choosen B
I think you have mistyped the problem. it could have been 5^12, 5^13
in that case:
diff = 5^13-5^12 = 5^12(5-1)= 4*5^12
now A = 5^12 - 2(4*5^12)
A=5^12(1-8)
=(-7)5^12
pick D
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by singhpreet1 » Fri Jul 16, 2010 10:24 pm
pradeepkaushal9518 wrote:A.........B........C.........D

The integers A, B, C, and D shown on the number line above are all equally spaced. If C and D are equal to 512 and 513,
respectively, what is the value of A?

511
510
-512
(-7)512
(-12)513

i have choosen B
B is fine. that is the only option which satisfies the condition. working backwards. D is 513, C is 512, B is 511 so A will be 510.

do you have the OA?

Preet
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by selango » Fri Jul 16, 2010 11:28 pm
IMO B

Since A,B,C,D are equally spaced,let says differ by constant k.

C=A+2k

512=A+2k

D=A+3k

513=A+3k

K=1

C=A+2k

512=A+2k

D=A+3k

513=A+3k

K=1

512=A+2

A=510
--Anand--
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by selango » Fri Jul 16, 2010 11:31 pm
If its 5^12 and 5^13 then the answer is D

C=A+2k

5^12=A+2k

D=A+3k

5^13=A+3k

k=5^13-5^12

=5^12(4)

C=A+2k

5^12=A+8.5^12

A=-7(5^12)

Hence D
--Anand--
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by shashank.ism » Sat Jul 17, 2010 1:34 am
According to the given question the answer would be 510 i.e. B only ...but I don't think that would anyhow match a GMAT problem ..

I think kvcpk is correct and answer would be D.
preet would u tell if u have left " ^ " the power sign ..
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by singhpreet1 » Sat Jul 17, 2010 2:18 am
shashank.ism wrote:According to the given question the answer would be 510 i.e. B only ...but I don't think that would anyhow match a GMAT problem ..

I think kvcpk is correct and answer would be D.
preet would u tell if u have left " ^ " the power sign ..
i agree with you on that. if the question was as is looks it would not qualify as a GMAT question. but if there is an edit to the question by pradeepkaushal9518 we would be able to solve it. though D is fine if you go with 5^12 and 5 ^13

Preet
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