November 18, 2018 November 18, 2018 07:00 AM PST 09:00 AM PST Get personalized insights on how to achieve your Target Quant Score. November 18th, 7 AM PST November 20, 2018 November 20, 2018 09:00 AM PST 10:00 AM PST The reward for signing up with the registration form and attending the chat is: 6 free examPAL quizzes to practice your new skills after the chat.
Author 
Message 
TAGS:

Hide Tags

Current Student
Joined: 30 Dec 2015
Posts: 188
Location: United States
Concentration: Strategy, Organizational Behavior
GPA: 3.88
WE: Business Development (Hospitality and Tourism)

In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
28 Mar 2016, 08:50
Question Stats:
76% (02:12) correct 24% (02:17) wrong based on 664 sessions
HideShow timer Statistics
In a certain quiz that consists of 10 questions, each question after the first is worth 4 points more than the preceding question. If the 10 questions on the quiz are worth a total of 360 points, how many points is the third question worth? A. 18 B. 24 C. 26 D. 32 E. 44
Official Answer and Stats are available only to registered users. Register/ Login.




Math Expert
Joined: 02 Aug 2009
Posts: 7036

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
28 Mar 2016, 09:11
lpetroski wrote: In a certain quiz that consists of 10 questions, each question after the first is worth 4 points more than the preceding question. If the 10 questions on the quiz are worth a total of 360 points, how many points is the third question worth? A. 18 B. 24 C. 26 D. 32 E. 44 Hi, If we look at the increase, it tells us that it is a arithmetic expression..let the first number be x.. so \(SUM of 1st 10= x+4+x+x+8+....x+4*9\).. so \(SUM = 10x+4(1+2+..+9)=360\) 10x+180=360.. 10x=180 or x=18.. so 3rd number= 18+4*2=26C
_________________
1) Absolute modulus : http://gmatclub.com/forum/absolutemodulusabetterunderstanding210849.html#p1622372 2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html 3) effects of arithmetic operations : https://gmatclub.com/forum/effectsofarithmeticoperationsonfractions269413.html
GMAT online Tutor




Current Student
Joined: 07 Jan 2015
Posts: 82
Location: Thailand
GMAT 1: 540 Q41 V23 GMAT 2: 570 Q44 V24 GMAT 3: 550 Q44 V21 GMAT 4: 660 Q48 V33
GPA: 3.31
WE: Science (Other)

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
28 Mar 2016, 18:17
Equation is like this:
\(10x + ( 4 + 8 + 12 + ... + 32) = 360\)
to find sum of the evenly spaced sequence, use average * number of the members in the sequence
\(10x + (20*9) = 360\)
\(10x + 180 = 360\) \(x = 18\)
So, \(x + 8 = 26\)




Senior Manager
Joined: 15 Oct 2015
Posts: 322
Concentration: Finance, Strategy
GPA: 3.93
WE: Account Management (Education)

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
12 Apr 2016, 03:34
Aves wrote: Equation is like this:
\(10x + ( 4 + 8 + 12 + ... + 32) = 360\)
to find sum of the evenly spaced sequence, use average * number of the members in the sequence
\(10x + (20*9) = 360\)
\(10x + 180 = 360\) \(x = 18\)
So, \(x + 8 = 26\) chetan went the orthodox way. But Aves chose the short cut and ended up creating confusion in middle of the solution. Quote: to find sum of the evenly spaced sequence, use average * number of the members in the sequence i understand that very well. What you did further was like you forgot what you said above.



Intern
Joined: 17 Jan 2016
Posts: 10

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
05 May 2016, 08:19
Aves wrote: Equation is like this:
\(10x + ( 4 + 8 + 12 + ... + 32) = 360\)
to find sum of the evenly spaced sequence, use average * number of the members in the sequence
\(10x + (20*9) = 360\)
\(10x + 180 = 360\) \(x = 18\)
So, \(x + 8 = 26\) Thanks for the detailed explanation, helped a lot. But the red 32 has to be a 36, right?



Current Student
Joined: 23 Feb 2015
Posts: 167

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
22 May 2016, 11:23
Aves wrote: Equation is like this:
\(10x + ( 4 + 8 + 12 + ... + 32) = 360\)
to find sum of the evenly spaced sequence, use average * number of the members in the sequence
\(10x + (20*9) = 360\)
\(10x + 180 = 360\) \(x = 18\)
So, \(x + 8 = 26\) Good shortcut  will use this in the future. I did it the long way but still got the question right in about 90 seconds x x+4 x+8 x+12 x+16 x+20 x+24 x+28 x+32 x+36 10x+180=360 10x=180 x=18 3rd question = x+8 = 18+8 = 26 Answer C



Intern
Joined: 06 Jun 2016
Posts: 1

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
01 Aug 2016, 11:18
I found a shortcut for the same. Since we know that there are 10 questions on the quiz and all questions are evenly placed by 4 points, DO NOT choose the points in the first question as x.
INSTEAD, choose it as x16. So, the numbers will be: 1) x16 2) x12 3) x8 4) x4 5) x 6) x+4 7) x+8 8) x+12 9) x+16 10) x+20
Adding all the above 10 will lead to a simple sum of 10x + 20 (16 & 16 will lead to a sum of 0, same for 12& +12 so on & so forth)
SO, 10x + 20 = 360 10x= 340 x= 34 3rd question = x8= 348 = 26.
Hope it helps.



Intern
Joined: 24 Aug 2016
Posts: 29

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
09 Sep 2016, 11:28
Dondarrion wrote: Aves wrote: Equation is like this:
\(10x + ( 4 + 8 + 12 + ... + 32) = 360\)
to find sum of the evenly spaced sequence, use average * number of the members in the sequence
\(10x + (20*9) = 360\)
\(10x + 180 = 360\) \(x = 18\)
So, \(x + 8 = 26\) Good shortcut  will use this in the future. I did it the long way but still got the question right in about 90 seconds x x+4 x+8 x+12 x+16 x+20 x+24 x+28 x+32 x+36 10x+180=360 10x=180 x=18 3rd question = x+8 = 18+8 = 26 Answer C I did it this way also. The quick way to do this math is x + 4(sum of 1 through 9) = x + 4(45) = x + 180 (Sum of 1 through 9) is found by: Average of first and last term * number of terms = 1 + 9 = 10/2 = 51 through 9 = 9 terms 9*5 = 45



Senior Manager
Joined: 18 Jun 2016
Posts: 262
Location: India
GMAT 1: 720 Q50 V38 GMAT 2: 750 Q49 V42
GPA: 4
WE: General Management (Other)

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
27 Sep 2016, 11:12
lpetroski wrote: In a certain quiz that consists of 10 questions, each question after the first is worth 4 points more than the preceding question. If the 10 questions on the quiz are worth a total of 360 points, how many points is the third question worth? A. 18 B. 24 C. 26 D. 32 E. 44 This is an Arithmetic Progression (A.P.) with terms => a, a+4, a+8, ...., a + (n1) *4 a => First Term of Series n => Number of the term l => Last Term So, l = a + (101) * 4 = a + 9*4 = a + 36 Sum of an A.P. Series = \(\frac{n*(a+l)}{2}\) => Standard Formula Therefore, \(360 = \frac{n*(a+l)}{2} => 360 = \frac{10*(a+a+36)}{2}\) => 360 = 5 * (2a + 36) => 72 = 2a + 36 => 2a = 36 => a = 18 Therefore, 3rd Term = a + 8 = 26
_________________
I'd appreciate learning about the grammatical errors in my posts
Please hit Kudos If my Solution helps
My Debrief for 750  https://gmatclub.com/forum/from720to750oneofthemostdifficultpleatuestoovercome246420.html
My CR notes  https://gmatclub.com/forum/patternsincrquestions243450.html



Intern
Joined: 14 Oct 2016
Posts: 30
Location: India
WE: Sales (Energy and Utilities)

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
08 Sep 2017, 19:28
I got this in a similar approach but we can calculate and get answer in 50 Secs. Since the seq is in AP evenly spaced the sum= Avg* N Seq is x,x+4, x+2*4,x+3*4, x+4*4,x+5*4,x+6*4,x+7*4,x+8*4,x+9*4 ( don't need to write the entire seq just get the idea how seq is going to form ) and so on the average of evenly spaced set of 10 numbers is average of 5th and 6th value. Since each term is increment of 4 the mid value between 5 and 6 will be increment of 2 from 5th value so fifth value is x+4*4= x+16 so average is x+18 so (x+18)*10=360 x+18=36 or x=18 and third value is x+2*4=18+8= 26 The trick in above question is identifying the evenly spaced seq, then its average or median value and finding x.
_________________
Abhimanyu



Intern
Joined: 31 Oct 2017
Posts: 6
Location: United States (CA)
Concentration: Leadership, Technology
GPA: 3.17

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
14 Feb 2018, 22:32
since we have 10 items on this list, starting with n and ending with n+36, I used empowergmat's bunching method: (note that this is useful for lists that have consecutive forms, in this case with +4 increments) method: Add the first and Last number, then multiply it by half of the number of the items, in this case 5 (given our 10 item list) so, (n + n + 36) * 5 should equal to 360 > 2n + 36 = 72 > 2n = 36 > n = 18 since we are looking for 3rd item, that's n + 8, which is 18 + 8 = 26 EMPOWERgmatRichC please let me know if I used the method correctly... not sure if I had ever used bunching in a sequence question like this, but it def appeared to have worked.



Intern
Joined: 30 Nov 2017
Posts: 41

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
15 Feb 2018, 03:36
This is an Arithmetic progression question.
n/2 * [2a + (n  1) *d] = 360 10/2 * [2a + (10  1)* 4)] = 360 a = 18
So, first question is 18 marks.
So, third question = 26



Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 4170
Location: United States (CA)

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
19 Feb 2018, 09:43
lpetroski wrote: In a certain quiz that consists of 10 questions, each question after the first is worth 4 points more than the preceding question. If the 10 questions on the quiz are worth a total of 360 points, how many points is the third question worth? A. 18 B. 24 C. 26 D. 32 E. 44 The first question is worth x, the 2nd worth x + 4, the 3rd worth x + 2(4) = x + 8, ..., the 10th is worth x + 9(4) = x + 36. Since we have a set of evenlyspaced numbers, the average is (x + x + 36)/2 = (2x + 36)/2 = x + 18. Since sum = average * quantity we have: 360 = (x + 18) * 10 36 = x + 18 18 = x The first question is worth x = 18 points. So the third question is worth x + 8 = 18 + 8 = 26 points. Answer: C
_________________
Scott WoodburyStewart
Founder and CEO
GMAT Quant SelfStudy Course
500+ lessons 3000+ practice problems 800+ HD solutions



Senior Manager
Status: love the club...
Joined: 24 Mar 2015
Posts: 267

In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
18 Mar 2018, 17:33
lpetroski wrote: In a certain quiz that consists of 10 questions, each question after the first is worth 4 points more than the preceding question. If the 10 questions on the quiz are worth a total of 360 points, how many points is the third question worth? A. 18 B. 24 C. 26 D. 32 E. 44 10x + 4 (1 + 2 + 3 + ....9) = 360 =) 10x + 4 * [n(n+1)]/2 = 360 =) 10x + 4 * [(9 * 10)] / 2 = 360 =) x = 18 third question = (18 +8) =26 = C the answer thakns



Manager
Joined: 31 Oct 2016
Posts: 108

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
25 Jul 2018, 23:51
There is no need for any formulas here. Sum of 10 consecutive integers = 360. Average = 36. Average of a set of consecutive integers = Median of the set. Median is the number between 5 and 6, and its equals 36.
Since the difference between terms is 4, therefore, 5th term is 34 and 6th term is 38. 5th term = 34 4th term = 30 3th term = 26



Intern
Joined: 10 Oct 2017
Posts: 6

Re: In a certain quiz that consists of 10 questions, each question after
[#permalink]
Show Tags
27 Jul 2018, 09:23
lpetroski wrote: In a certain quiz that consists of 10 questions, each question after the first is worth 4 points more than the preceding question. If the 10 questions on the quiz are worth a total of 360 points, how many points is the third question worth? A. 18 B. 24 C. 26 D. 32 E. 44 If we assume first question is worth "x" points, the proceeding questions would be worth x+4, x+8, x+12,.... x+36 points. So, the sum of 10 questions would be 10x plus the sum of 4  36 inclusive, with multiples of 4 (4, 8, 12, 16, 20, 24, 28, 32, 36). The sum of 436 can be calculated with (4+36)/4*(16+20)/2 = 180. (The first and last numbers in the list divided by 4, times the average of the numbers (16+20)/2=18) Therefore, the total sum would be 10x + 180 = 360, x= 18. Finally the third question was worth x+8 = 18+6 = 26 points.




Re: In a certain quiz that consists of 10 questions, each question after &nbs
[#permalink]
27 Jul 2018, 09:23






