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Given that x& = x^2 + 3, what is the value of integer k if there is a

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Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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Updated on: 24 Jan 2018, 03:42
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Given that x& = x^2 + 3, what is the value of integer k if there is a remainder of 3 when k& is divided by 4?

(1) 16 < k& < 37
(2) k is a factor of 24.

(A). In statement 1, there are two possible
values for k&: 19 and 28. Only 19 has a
11
The Princeton Review Management, LLC 2002
remainder of 3 when divided by 4,
however, so statement 1 is sufficient. All
even values of k will have a remainder of
3 when divided by 4 (can you explain why
this is so?), so statement 2 does not give
you enough information.

Can someone please explain this to me? Why are 19 and 28 the only possibility in statement 1?

Originally posted by nehalkapadi123 on 24 Jan 2018, 02:44.
Last edited by Bunuel on 24 Jan 2018, 03:42, edited 3 times in total.
Renamed the topic, edited the question and the OA.
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Re: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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24 Jan 2018, 03:25
Given that x& = x^2 + 3, what is the value of integer k if there is a remainder of 3 when k& is divided by 4?

(1) 16 < k& < 37
(2) k is a factor of 24.

Can someone please explain this to me? Why are 19 and 28 the only possibility in statement 1?

hi K&=K^2+3..
so k^2+3 when divided by 4 leaves a remainder of 3..
so K^2 must be divisible by 4... so k could be any even number

1)16<K&<37
$$16<K^2+3<37$$....
$$K^2+3>16.....K^2>13...$$ so K >3 and K is an integer
$$K^2+3<37.....K^2<36..$$ .so K<6
possible values of K are 4 and 5
but 5^2 is not div by 4, so our answer 4..
suff

2) K is a factor of 24
nothing much
insuff

A
_________________

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: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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24 Jan 2018, 03:31
chetan2u wrote:
Given that x& = x^2 + 3, what is the value of integer k if there is a remainder of 3 when k& is divided by 4?

(1) 16 < k& < 37
(2) k is a factor of 24.

Can someone please explain this to me? Why are 19 and 28 the only possibility in statement 1?

hi K&=K^2+3..
so k^2+3 when divided by 4 leaves a remainder of 3..
so K^2 must be divisible by 4... so k could be any even number

1)16<K&<37
$$16<K^2+3<37$$....
$$K^2+3>16.....K^2>13...$$ so K >3 and K is an integer
$$K^2+3<37.....K^2<36..$$ .so K<6
possible values of K are 4 and 5
but 5^2 is not div by 4, so our answer 4..
suff

2) K is a factor of 24
nothing much
insuff

A

This would be correct if we were told that k is a positive integer. From (1) k could also be -4. (2) indirectly tells us that k must be positive, so the answer is C. Not a good question overall.
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Re: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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24 Jan 2018, 03:37
Bunuel wrote:
chetan2u wrote:
Given that x& = x^2 + 3, what is the value of integer k if there is a remainder of 3 when k& is divided by 4?

(1) 16 < k& < 37
(2) k is a factor of 24.

Can someone please explain this to me? Why are 19 and 28 the only possibility in statement 1?

hi K&=K^2+3..
so k^2+3 when divided by 4 leaves a remainder of 3..
so K^2 must be divisible by 4... so k could be any even number

1)16$$16\(K^2+3>16.....K^2>13...$$ so K >3 and K is an integer
$$K^2+3<37.....K^2<36..$$ .so K<6
possible values of K are 4 and 5
but 5^2 is not div by 4, so our answer 4..
suff

2) K is a factor of 24
nothing much
insuff

A

This would be correct if we were told that k is a positive integer. From (1) k could also be -4. (2) indirectly tells us that k must be positive, so the answer is C. Not a good question overall.

yes I agree Bunuel..
and I doubt in GMAT a statement like " k is a factor of 24" would be given to give the info that k is positive..
_________________

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: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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24 Jan 2018, 03:40
chetan2u wrote:
Bunuel wrote:
chetan2u wrote:

This would be correct if we were told that k is a positive integer. From (1) k could also be -4. (2) indirectly tells us that k must be positive, so the answer is C. Not a good question overall.

yes I agree Bunuel..
and I doubt in GMAT a statement like " k is a factor of 24" would be given to give the info that k is positive..

Yes. That's one reason I think the question is not good.
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Re: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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24 Jan 2018, 06:15
chetan2u wrote:
Given that x& = x^2 + 3, what is the value of integer k if there is a remainder of 3 when k& is divided by 4?

(1) 16 < k& < 37
(2) k is a factor of 24.

Can someone please explain this to me? Why are 19 and 28 the only possibility in statement 1?

hi K&=K^2+3 ..
so k^2+3 when divided by 4 leaves a remainder of 3..
so K^2 must be divisible by 4... so k could be any even number

Can someone explain to me what is going on here? The question states "x& = x^2 + 3" so why do you conclude "K&=K^2+3"??
1)16<K&<37
$$16<K^2+3<37$$....
$$K^2+3>16.....K^2>13...$$ so K >3 and K is an integer
$$K^2+3<37.....K^2<36..$$ .so K<6
possible values of K are 4 and 5
but 5^2 is not div by 4, so our answer 4..
suff

2) K is a factor of 24
nothing much
insuff

A
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Joined: 02 Aug 2009
Posts: 7212
Re: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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24 Jan 2018, 06:29
HarryAxel wrote:
chetan2u wrote:
Given that x& = x^2 + 3, what is the value of integer k if there is a remainder of 3 when k& is divided by 4?

(1) 16 < k& < 37
(2) k is a factor of 24.

Can someone please explain this to me? Why are 19 and 28 the only possibility in statement 1?

hi K&=K^2+3 ..
so k^2+3 when divided by 4 leaves a remainder of 3..
so K^2 must be divisible by 4... so k could be any even number

Can someone explain to me what is going on here? The question states "x& = x^2 + 3" so why do you conclude "K&=K^2+3"??
1)16<K&<37
$$16<K^2+3<37$$....
$$K^2+3>16.....K^2>13...$$ so K >3 and K is an integer
$$K^2+3<37.....K^2<36..$$ .so K<6
possible values of K are 4 and 5
but 5^2 is not div by 4, so our answer 4..
suff

2) K is a factor of 24
nothing much
insuff

A

Hi..

x isa variable and it is basically given to tell you about function '&' ..
x can take any value as it is a variable...
Ofcourse it could have been given as X& too..
_________________

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: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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24 Jan 2018, 06:41
Ok but it is not stated that "&" is a function right? It could be a number so how can we tell?
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Re: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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24 Jan 2018, 22:15
HarryAxel wrote:
Ok but it is not stated that "&" is a function right? It could be a number so how can we tell?

I believe in GMAT it would be explicitly mentioned. Here its not explicitly mentioned, then we go by the conventions - what we generally follow. We use 'x', 'y', 'z' etc to represent variables (which are supposed to take various numerical values), but we dont use symbols like '&', '\$', '#' etc to represent numbers - these are used for some specific purposes, one of which is to 'define a function'. Eg, here '&' has been defined as a function before which whenever you place any number, you have a result which is square of that placed number and then 3 added.

So, 5& becomes = 5^2 + 3 = 28.
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Posts: 52344
Re: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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24 Jan 2018, 22:25
HarryAxel wrote:
Ok but it is not stated that "&" is a function right? It could be a number so how can we tell?

As mentioned above, this is not a good question, so you can ignore it and move on.

For more on functions check the links below:

13. Functions

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Posts: 7
Re: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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25 Jan 2018, 20:39
Just a quick question:
If we are told K is a factor, couldn’t K be a negative number?

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Re: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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25 Jan 2018, 20:40
balhhs0e wrote:
Just a quick question:
If we are told K is a factor, couldn’t K be a negative number?

Sent from my iPhone using GMAT Club Forum mobile app

A factor is a positive divisor.
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Re: Given that x& = x^2 + 3, what is the value of integer k if there is a  [#permalink]

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25 Jan 2018, 20:44
Thank you. A multiple could be negative, but NOT a factor. Clear!!!

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Re: Given that x& = x^2 + 3, what is the value of integer k if there is a &nbs [#permalink] 25 Jan 2018, 20:44
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