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The population of Town X on January 1, 2010, was 56 percent greater...

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The population of Town X on January 1, 2010, was 56 percent greater...  [#permalink]

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08 Jul 2018, 08:55
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25% (medium)

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80% (01:02) correct 20% (01:44) wrong based on 30 sessions

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The population of Town X on January 1, 2010, was 56 percent greater than the population of the same town on January 1, 2005. The population of Town X on January 1, 2015, was 75 percent greater than the population of the same town on January 1, 2010. What was the population of Town X on January 1, 2005?

(1) The population of Town X on January 1, 2015, was 21,840.

(2) The increase in the population of Town X from January 1, 2010, to January 1, 2015, was 4,880 greater than the increase in the population of Town X from January 1, 2005, to January 1, 2010.

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Manish

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The population of Town X on January 1, 2010, was 56 percent greater...  [#permalink]

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08 Jul 2018, 09:20
CAMANISHPARMAR wrote:
The population of Town X on January 1, 2010, was 56 percent greater than the population of the same town on January 1, 2005. The population of Town X on January 1, 2015, was 75 percent greater than the population of the same town on January 1, 2010. What was the population of Town X on January 1, 2005?

(1) The population of Town X on January 1, 2015, was 21,840.

(2) The increase in the population of Town X from January 1, 2010, to January 1, 2015, was 4,880 greater than the increase in the population of Town X from January 1, 2005, to January 1, 2010.

let the population of town X be X in 2005..
so in 2010 it becomes 1.56X and in 2015 it becomes 1.75*1.56X..
so all the populations are in term of X

if you know population of any one of the year, you will get X

(1) The population of Town X on January 1, 2015, was 21,840.
so 1.75*1.56X=21840
we can get X
suff

(2) The increase in the population of Town X from January 1, 2010, to January 1, 2015, was 4,880 greater than the increase in the population of Town X from January 1, 2005, to January 1, 2010.
so 1.75*1.56X-1.56X=4880+1.56X-X
so you have one term free of variable and rest all terms in X, we can find X
Suff

D
we dont have to try to find the values. knowing that equation will give us a value, Move ahead

Edit: Edited typo

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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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Re: The population of Town X on January 1, 2010, was 56 percent greater...  [#permalink]

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09 Jul 2018, 02:07
CAMANISHPARMAR wrote:
The population of Town X on January 1, 2010, was 56 percent greater than the population of the same town on January 1, 2005. The population of Town X on January 1, 2015, was 75 percent greater than the population of the same town on January 1, 2010. What was the population of Town X on January 1, 2005?

(1) The population of Town X on January 1, 2015, was 21,840.

(2) The increase in the population of Town X from January 1, 2010, to January 1, 2015, was 4,880 greater than the increase in the population of Town X from January 1, 2005, to January 1, 2010.

Let X be the population of town X on Jan 1 2005.

Hence population on Jan 1 2010 = 1.56X

& population on Jan 1 2015 = (1.56)(1.75)X

Statement 1: 21840 = (1.56)(1.75)X

We can find X. Statement 1 alone is Sufficient.

Statement 2: (1.56)(1.75)X - 1.56X = 1.56X - X + 4880

We can find X. Statement 2 alone is Sufficient.

Thanks,
GyM
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Re: The population of Town X on January 1, 2010, was 56 percent greater... &nbs [#permalink] 09 Jul 2018, 02:07
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