GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 19 Jan 2019, 16:54

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel
Events & Promotions in January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
  • FREE Quant Workshop by e-GMAT!

     January 20, 2019

     January 20, 2019

     07:00 AM PST

     07:00 AM PST

    Get personalized insights on how to achieve your Target Quant Score.
  • Free GMAT Strategy Webinar

     January 19, 2019

     January 19, 2019

     07:00 AM PST

     09:00 AM PST

    Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.

What is the sum of all multiples of 3 between 1 and 200?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6815
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
What is the sum of all multiples of 3 between 1 and 200?  [#permalink]

Show Tags

New post 28 Aug 2018, 01:07
1
5
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

75% (01:41) correct 25% (01:23) wrong based on 67 sessions

HideShow timer Statistics

[Math Revolution GMAT math practice question]

What is the sum of all multiples of 3 between 1 and 200?

A. 3300
B. 6600
C. 6633
D. 10100
E. 20100

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $149 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Director
Director
User avatar
P
Joined: 18 Jul 2018
Posts: 574
Location: India
Concentration: Finance, Marketing
WE: Engineering (Energy and Utilities)
Premium Member Reviews Badge CAT Tests
Re: What is the sum of all multiples of 3 between 1 and 200?  [#permalink]

Show Tags

New post 28 Aug 2018, 01:31
1
1
\(T_n\) (Last Term) = a+(n-1)d

a - First term
d - Common Difference
n - Number of terms

The multiples of 3 from 1 to 200 are 3,6,9,12,....,198
a = 3
d = 3
\(T_n\) = 198

Now, Using the formula

198 = 3+(n-1)3

Solving Gives,

n = 66

Now, Sum of all the terms in AP is given by

\(S_n\) = \(\frac{n}{2}\)[2a+(n-1)d]

\(S_{66}\) = \(\frac{66}{2}\)[2*3+(66-1)3]

\(S_{66}\) = 33[6+195]

\(S_{66}\) = 6633

C is the answer.
_________________

If you are not badly hurt, you don't learn. If you don't learn, you don't grow. If you don't grow, you don't live. If you don't live, you don't know your worth. If you don't know your worth, then what's the point?

VP
VP
User avatar
D
Joined: 09 Mar 2016
Posts: 1288
What is the sum of all multiples of 3 between 1 and 200?  [#permalink]

Show Tags

New post Updated on: 28 Aug 2018, 02:20
MathRevolution wrote:
[Math Revolution GMAT math practice question]

What is the sum of all multiples of 3 between 1 and 200?

A. 3300
B. 6600
C. 6633
D. 10100
E. 20100



here is my fantastic approach :)

Step One: NUMBER OF MULTIPLES using the formula below :)

NUMBER OF MULTIPLES X IN THE RANGE

\(\frac{last..multiple..of..x - first..multiple..of...x}{x}+1\)

\(\frac{198-3}{3}+1 = 66\)

Step Two: FIND THE SUM OF TERMS

SUM OF N TERMS = \(\frac{n}{2} (2a+(n-1)d)\)

\(a\) = 3 the first term
\(d\) = 3 distance
\(n\) = 66 how many terms to add up

\(\frac{66}{2} (2*3+(66-1)3)\)= \(6,633\)

For those who are curious and want to learn more about similar formulas, check this post :) https://gmatclub.com/forum/arithmetic-p ... 61976.html

Originally posted by dave13 on 28 Aug 2018, 02:17.
Last edited by dave13 on 28 Aug 2018, 02:20, edited 1 time in total.
Director
Director
User avatar
V
Joined: 06 Jan 2015
Posts: 567
Location: India
Concentration: Operations, Finance
GPA: 3.35
WE: Information Technology (Computer Software)
Premium Member
Re: What is the sum of all multiples of 3 between 1 and 200?  [#permalink]

Show Tags

New post 28 Aug 2018, 02:20
MathRevolution wrote:
[Math Revolution GMAT math practice question]

What is the sum of all multiples of 3 between 1 and 200?

A. 3300
B. 6600
C. 6633
D. 10100
E. 20100


n=(198-3)/3 +1 = 66

Sum = (first term + last term)*(n/2)

= (3+198)66/2 = 6633

Hence C
_________________

आत्मनॊ मोक्षार्थम् जगद्धिताय च

Resource: GMATPrep RCs With Solution

Manager
Manager
avatar
G
Joined: 20 Feb 2017
Posts: 164
Location: India
Concentration: Operations, Strategy
WE: Engineering (Other)
Re: What is the sum of all multiples of 3 between 1 and 200?  [#permalink]

Show Tags

New post 28 Aug 2018, 03:05
2
I saw the timer: it shows around 4 minutes, it took me 1 minute
Looking at the question you should know it's asking the sum of an AP
the series starts from 3 and ends with 198 (both inclusive)
Hence number of terms : 198-3/3+1 = 66
the sum = n/2(first term +last term )
=66/2(3+198)
= 33*201 (you don't' need to multiply here, check the last digit, it must end with 3, hence answer is C )
_________________

If you feel the post helped you then do send me the kudos (damn theya re more valuable than $)

VP
VP
User avatar
D
Joined: 09 Mar 2016
Posts: 1288
What is the sum of all multiples of 3 between 1 and 200?  [#permalink]

Show Tags

New post 28 Aug 2018, 03:26
1
Raksat wrote:
I saw the timer: it shows around 4 minutes



it was meeeeeeeeeee :grin: :lol:
Attachments

It-Was-Me-.gif
It-Was-Me-.gif [ 856.64 KiB | Viewed 850 times ]

Director
Director
User avatar
P
Joined: 31 Oct 2013
Posts: 953
Concentration: Accounting, Finance
GPA: 3.68
WE: Analyst (Accounting)
What is the sum of all multiples of 3 between 1 and 200?  [#permalink]

Show Tags

New post 28 Aug 2018, 04:54
1
MathRevolution wrote:
[Math Revolution GMAT math practice question]

What is the sum of all multiples of 3 between 1 and 200?

A. 3300
B. 6600
C. 6633
D. 10100
E. 20100



First Multiple = 3

Last Multiple = 198

3 + 6 + 9 + 12 + 15 + 18 + 21 ...................+ 198.

= 3 ( 1 + 2 + 3 + 4 + 5 + 6.........................+ 66)

Now we can find out the sum of consecutive integers up to 66 as follows;

\(\frac{n(n+1)}{2}\)

= \(\frac{66(66+1)}{2}\)

= 33*67

So, 3(67*33) is our answer.

Just multiply the unit digits. 3*7*3 = 3

Only option is C.


A 40 sec approach .
CEO
CEO
User avatar
D
Joined: 11 Sep 2015
Posts: 3341
Location: Canada
Re: What is the sum of all multiples of 3 between 1 and 200?  [#permalink]

Show Tags

New post 28 Aug 2018, 05:39
Top Contributor
MathRevolution wrote:
[Math Revolution GMAT math practice question]

What is the sum of all multiples of 3 between 1 and 200?

A. 3300
B. 6600
C. 6633
D. 10100
E. 20100


Useful formula: 1 + 2 + 3 + 4 + . . . n = (n)(n + 1)/2

We want to find the sum: 3 + 6 + 9 + 12 + . . . 198
Factor out the 3 to get: 3(1 + 2 + 3 + 4 + . . . 66)
Apply formula to get: 3(66)(67)/2
Evaluate to get: 6633

Answer: C

Cheers,
Brent
_________________

Test confidently with gmatprepnow.com
Image

GMATH Teacher
User avatar
G
Status: GMATH founder
Joined: 12 Oct 2010
Posts: 619
Re: What is the sum of all multiples of 3 between 1 and 200?  [#permalink]

Show Tags

New post 28 Aug 2018, 06:24
MathRevolution wrote:
What is the sum of all multiples of 3 between 1 and 200?

A. 3300
B. 6600
C. 6633
D. 10100
E. 20100

? = 3+6+9+ ... + 195 + 198

In any finite arithmetic progression, the (global) average is equal to the median and to the average of symmetric elements (to the median).

The first and last elements are always symmetrical, hence their average (3+198)/2 is equal to the (global) average.

How many terms are involved?

\(3 \leqslant 3M \leqslant 198\,\,\left( { = 180 + 18} \right)\,\,\,\,\,\,\,\,\mathop \Rightarrow \limits^{:\,\,\,3} \,\,\,\,\,\,1 \leqslant M\,\,\, \leqslant \,\,\,66\,\,\,\,\, \Rightarrow \,\,\,\,66\,\)

Using the homogeneity nature of the average we have:

\(? = 66 \cdot \frac{{\left( {3 + 198} \right)}}{2} = 33 \cdot 201\,\,\,\,\,\mathop \Rightarrow \limits^{choices} \,\,\,\,\,\left\langle ? \right\rangle = \left\langle {33 \cdot 201} \right\rangle = \left\langle 3 \right\rangle\)

\(\left\langle N \right\rangle \,\,\, = \,\,\,\,{\text{units}}\,\,{\text{digit}}\,\,{\text{of}}\,\,N\)

The above follows the notations and rationale taught in the GMATH method.
_________________

Fabio Skilnik :: GMATH method creator (Math for the GMAT)
Our high-level "quant" preparation starts here: https://gmath.net

VP
VP
avatar
P
Joined: 07 Dec 2014
Posts: 1152
Re: What is the sum of all multiples of 3 between 1 and 200?  [#permalink]

Show Tags

New post 28 Aug 2018, 11:27
MathRevolution wrote:
[Math Revolution GMAT math practice question]

What is the sum of all multiples of 3 between 1 and 200?

A. 3300
B. 6600
C. 6633
D. 10100
E. 20100


greatest multiple of 3=198
198/3=66 total multiples of 3
(198+3)/2=100.5
100.5*66=6633
C
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6815
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Re: What is the sum of all multiples of 3 between 1 and 200?  [#permalink]

Show Tags

New post 29 Aug 2018, 23:51
=>

We need to find the sum of \(3, 6, …, 198\).
The number of data values is \(\frac{(198 – 3)}{3} + 1 = \frac{195}{3} + 1 = 65 + 1 = 66.\)
Thus the sum of \(3, 6, …, 198\) is \(3 + 6 + … + 198 = 3+6+…+198=3(1+2+…+66)=\frac{3(66)(66+1)}{2}=3(33)(67)=6,633.\)

Therefore, the answer is C.
Answer: C
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $149 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

GMAT Club Bot
Re: What is the sum of all multiples of 3 between 1 and 200? &nbs [#permalink] 29 Aug 2018, 23:51
Display posts from previous: Sort by

What is the sum of all multiples of 3 between 1 and 200?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.