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

 It is currently 16 Jan 2019, 00:16

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

Events & Promotions

Events & Promotions in January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
• The winning strategy for a high GRE score

January 17, 2019

January 17, 2019

08:00 AM PST

09:00 AM PST

Learn the winning strategy for a high GRE score — what do people who reach a high score do differently? We're going to share insights, tips and strategies from data we've collected from over 50,000 students who used examPAL.
• 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 the first 50 multiples of a positive integer K?

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

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 52119
What is the sum of the first 50 multiples of a positive integer K?  [#permalink]

Show Tags

18 Apr 2018, 17:21
00:00

Difficulty:

35% (medium)

Question Stats:

63% (01:10) correct 37% (01:13) wrong based on 50 sessions

HideShow timer Statistics

What is the sum of the first 50 multiples of a positive integer K?

(A) 1,225K
(B) 1,275K
(C) 2,450K
(D) 2,550K
(E) 1,326K

_________________
Senior Manager
Joined: 29 Dec 2017
Posts: 386
Location: United States
Concentration: Marketing, Technology
GMAT 1: 630 Q44 V33
GMAT 2: 690 Q47 V37
GMAT 3: 710 Q50 V37
GPA: 3.25
WE: Marketing (Telecommunications)
What is the sum of the first 50 multiples of a positive integer K?  [#permalink]

Show Tags

18 Apr 2018, 18:23
1
Bunuel wrote:
What is the sum of the first 50 multiples of a positive integer K?

(A) 1,225K
(B) 1,275K
(C) 2,450K
(D) 2,550K
(E) 1,326K

We have to find Sum of progression (1+2+..+50)K = (50+1)/2*50 *K =1 275 K

Answer (B) 1,275K
Senior SC Moderator
Joined: 22 May 2016
Posts: 2329
What is the sum of the first 50 multiples of a positive integer K?  [#permalink]

Show Tags

19 Apr 2018, 10:28
Bunuel wrote:
What is the sum of the first 50 multiples of a positive integer K?

(A) 1,225K
(B) 1,275K
(C) 2,450K
(D) 2,550K
(E) 1,326K

Zero is a multiple of every integer.

The first 50 multiples of $$K$$ are
$$0K, 1K, 2K, 3K, . . . . 47K, 48K, 49K$$

Factor K out (we're interested in the arithmetic progression)

Sum of first 50 multiples of $$K$$:
$$K(0 + 1 + 2 + 3 . . . + 47 + 48 + 49)$$

Sum of evenly spaced integers=
(Average)*(# of terms)

Average = $$\frac{FirstTerm+LastTerm}{2}$$
Number of terms: 50 (given)

SUM (of K's multiples' coefficients) =
(Average)*(number of terms)

Sum: $$(\frac{(0 + 49)}{2}*50) = (25 * 49)= 1,225$$

Sum of first 50 multiples of K:
$$(1,225*K) = 1,225K$$

ANSWER A
_________________

Never look down on anybody unless you're helping them up.
--Jesse Jackson

CEO
Joined: 11 Sep 2015
Posts: 3318
Location: Canada
Re: What is the sum of the first 50 multiples of a positive integer K?  [#permalink]

Show Tags

19 Apr 2018, 11:59
1
Top Contributor
Bunuel wrote:
What is the sum of the first 50 multiples of a positive integer K?

(A) 1,225K
(B) 1,275K
(C) 2,450K
(D) 2,550K
(E) 1,326K

The answer to this question boils down to what is meant by "the first 50 multiples"
For example, some might say that the first 3 multiples of 5 are 5, 10, 15
Others might say that the first 3 multiples of 5 are 0, 5, 10
Of course, we might also even go in the other direction and say that the first 3 multiples of 5 are -5, -10, -15

I think the test-makers would add a few extra words to remove any ambiguity.

Cheers,
Brent
_________________

Test confidently with gmatprepnow.com

Re: What is the sum of the first 50 multiples of a positive integer K? &nbs [#permalink] 19 Apr 2018, 11:59
Display posts from previous: Sort by

What is the sum of the first 50 multiples of a positive integer K?

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

 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®.