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# In the equation above, k is a constant. If y = 17 when x = 2

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In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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01 Oct 2012, 05:07
00:00

Difficulty:

5% (low)

Question Stats:

95% (00:36) correct 5% (00:30) wrong based on 1396 sessions

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The Official Guide for GMAT® Review, 13th Edition - Quantitative Questions Project

y = kx + 3

In the equation above, k is a constant. If y = 17 when x = 2, what is the value of y when x = 4 ?

(A) 34
(B) 31
(C) 14
(D) 11
(E) 7

Practice Questions
Question: 54
Page: 159
Difficulty: 600

GMAT Club is introducing a new project: The Official Guide for GMAT® Review, 13th Edition - Quantitative Questions Project

Each week we'll be posting several questions from The Official Guide for GMAT® Review, 13th Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.

We'll be glad if you participate in development of this project:
2. Please vote for the best solutions by pressing Kudos button;
3. Please vote for the questions themselves by pressing Kudos button;
4. Please share your views on difficulty level of the questions, so that we have most precise evaluation.

Thank you!
[Reveal] Spoiler: OA

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Kudos [?]: 133137 [0], given: 12415

Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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01 Oct 2012, 05:08
SOLUTION

y = kx + 3

In the equation above, k is a constant. If y = 17 when x = 2, what is the value of y when x = 4 ?

(A) 34
(B) 31
(C) 14
(D) 11
(E) 7

Since if $$y = 17$$ when $$x = 2$$, then $$17 = 2k + 3$$ --> $$k=7$$.

Thus, $$y = 7x + 3$$. When $$x=4$$, $$y = 7*4 + 3=31$$.

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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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01 Oct 2012, 05:17
1
KUDOS
$$y = kx + 3$$ is the equation of the slope but in this context the question is different

$$y = K * 2 + 3$$to have y = 17 then K must be 7

$$17 = 7*2 + 3$$

$$y = 7*4 + 3$$ ---> $$y = 31$$

B must be the answer. Sub 600

Thanks
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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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01 Oct 2012, 19:53
Same explanation as Carcass's
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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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04 Oct 2012, 00:43

Explanation is same as provided by Carcass above.

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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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04 Oct 2012, 02:47
2
KUDOS
1) Put y =17 and x=2 and solve for K
2) Knowing k=7 from above and x=4 solve for Y ------> Y=31

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Math Expert
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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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04 Oct 2012, 14:14
SOLUTION

y = kx + 3

In the equation above, k is a constant. If y = 17 when x = 2, what is the value of y when x = 4 ?

(A) 34
(B) 31
(C) 14
(D) 11
(E) 7

Since if $$y = 17$$ when $$x = 2$$, then $$17 = 2k + 3$$ --> $$k=7$$.

Thus, $$y = 7x + 3$$. When $$x=4$$, $$y = 7*4 + 3=31$$.

Kudos points given to everyone with correct solution. Let me know if I missed someone.
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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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05 Oct 2012, 03:23
1 st step : solve given eqn for K by putting values of x and y. u get k=7
snd step : now put banck value of k=7 and x=4 in given eqn and solve for y.
you get y=31

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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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10 Dec 2012, 04:47
y = kx + 3
17 = k(2) + 3 --> 14 = 2k --> k=7

y = (7)(4) + 3 --> y = 31

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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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10 Sep 2014, 19:16
Bunuel wrote:
The Official Guide for GMAT® Review, 13th Edition - Quantitative Questions Project

y = kx + 3

In the equation above, k is a constant. If y = 17 when x = 2, what is the value of y when x = 4 ?

(A) 34
(B) 31
(C) 14
(D) 11
(E) 7

Practice Questions
Question: 54
Page: 159
Difficulty: 600

GMAT Club is introducing a new project: The Official Guide for GMAT® Review, 13th Edition - Quantitative Questions Project

Each week we'll be posting several questions from The Official Guide for GMAT® Review, 13th Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.

We'll be glad if you participate in development of this project:
2. Please vote for the best solutions by pressing Kudos button;
3. Please vote for the questions themselves by pressing Kudos button;
4. Please share your views on difficulty level of the questions, so that we have most precise evaluation.

Thank you!

given
y=kx+3

y=17 ; x=2

k = 4.

y=? if x = 7

y=31

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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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30 May 2016, 05:28
Bunuel wrote:
The Official Guide for GMAT® Review, 13th Edition - Quantitative Questions Project

y = kx + 3

In the equation above, k is a constant. If y = 17 when x = 2, what is the value of y when x = 4 ?

(A) 34
(B) 31
(C) 14
(D) 11
(E) 7

We are given the equation y = kx + 3, where k is a constant.

We are also given that y = 17 when x = 2, so we can plug these values into the equation to first determine a value for k.
y = kx + 3

17 = 2k + 3

14 = 2k

k = 7

We now can determine the value of y when x = 4:

y = kx + 3

y = (7)(4) + 3

y = 28 + 3

y = 31

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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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30 May 2016, 06:11
Bunuel wrote:
The Official Guide for GMAT® Review, 13th Edition - Quantitative Questions Project

y = kx + 3

In the equation above, k is a constant. If y = 17 when x = 2, what is the value of y when x = 4 ?

(A) 34
(B) 31
(C) 14
(D) 11
(E) 7

Given: y = kx + 3
Putting values of y and x.

17 = 2k+3; 2k = 14; k = 7.

Once k is known, I can calculate y for any value of x.

y = kx + 3
= {(7) * 4} +3
= 31

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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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20 Jun 2016, 15:47
The approach is right as seen above.
But I doubt that this question is a 600 difficulty question.
Maybe sub-600 more obviously.
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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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10 Aug 2017, 12:10
y = kx + 3

In the equation above, k is a constant. If y = 17 when x = 2, what is the value of y when x = 4 ?

(A) 34
(B) 31
(C) 14
(D) 11
(E) 7

May as well to use such approach:
If y = 17 when x = 2 -> 17 = 2k+3
When x = 4, y = 4k+3 = 2*(2k+3)-3=2*17-3=31

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Re: In the equation above, k is a constant. If y = 17 when x = 2 [#permalink]

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20 Aug 2017, 16:10
My approach inspired by a video I saw on GMATPrepNow was pretty quick.
I saw the y intercept in the equation "y = kx + 3" = 3 which implies coordinate (0,3)
Then the question gave away another coordinate (2,17) which shows that there was a 14 point rise in y with a 2 point run in x
Hence, another 2 point run in x makes x=4 and y=17+14=31

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Re: In the equation above, k is a constant. If y = 17 when x = 2   [#permalink] 20 Aug 2017, 16:10
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