Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Apr 2512:30 AM EDT
-01:30 AM EDT
At one point, she believed GMAT wasn’t for her. After scoring 595, self-doubt crept in and she questioned her potential. But instead of quitting, she made the right strategic changes. The result? A remarkable comeback to 695. Check out how Saakshi did it.
Apr 2601:30 AM EDT
-02:30 AM EDT
Learn how Keshav, a Chartered Accountant, scored an impressive 705 on GMAT in just 30 days with GMATWhiz's expert guidance. In this video, he shares preparation tips and strategies that worked for him, including the mock, time management, and more.
Apr 2610:00 AM EDT
-11:00 AM EDT
The Target Test Prep course represents a quantum leap forward in GMAT preparation, a radical reinterpretation of the way that students should study. Try before you buy with a 5-day, full-access trial of the course for FREE!
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
May 0111:00 AM PDT
-12:00 PM PDT
Free- full-length test + 15 concept videos + 150+ short videos + study plan!
Thelegend2631
Posts: 371
Updated on: 26 Jun 2021, 22:24
Originally posted by Thelegend2631 on 26 Jun 2021, 01:44.
Last edited by Thelegend2631 on 26 Jun 2021, 22:24, edited 2 times in total.
Last edited by Thelegend2631 on 26 Jun 2021, 22:24, edited 2 times in total.
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
95%
(hard)
Question Stats:
18% (03:07) correct
82%
(02:21)
wrong
based on 72
sessions
History
Date
Time
Result
Not Attempted Yet
How many ways can 720 be expressed as a sum of n Consecutive positive Integers ? ( n > 1 )
A. 3
B. 2
C. 5
D. 4
E. None of the above
A. 3
B. 2
C. 5
D. 4
E. None of the above
26 Jun 2021, 06:38
Kudos
Bookmarks
hD13
We can use the property of sum of n consecutive integers=n*average of the numbers.
Also, average of consecutive integers is the middle or median of the numbers.
Average when n is even
The average of the integers must be a decimal of the form xy.5, as it is middle of two consecutive numbers.
And when do we have that?: When we have just one 2 extra in the divisor
\(720=2^4*3^2*5\)
1) We have \(2^4\) in 720, so \(2^5\) will get a decimal of the form xy.5
\(\frac{720}{2^5}=22.5\)
32*22.5….n=32
7,8,9,….,21,22,23,24,…..36,37,38
2) We have \(2^4*3^2\) in 720, so \(2^5*3^2\) will get a decimal of the form xy.5
\(\frac{720}{2^5*3^2}=2.5\)
But this will get negative integers too.
3) We have \(5*2^4\) in 720, so \(5*2^5\) will get a decimal of the form xy.5
\(\frac{720}{5*2^5}=4.5\)
But this too will get negative integers.
Average when n is odd
The average of the integers will be an integer.
And when do we have that?: When we divide by an odd factor.
\(720=2^4*3^2*5\)
1) We have \(3\) in 720, so
\(\frac{720}{3}=240\)
3*240….n=3
239,240,241
2) We have \(3^2\) in 720, so
\(\frac{720}{3^2}=80\)
9*80….n=9
76,77,78,79,80,81,82,83,84
3) We have \(5\) in 720, so
\(\frac{720}{5}=144\)
5*144….n=5
142,143,144,145,146
4) We have \(3*5\) in 720, so
\(\frac{720}{3*5}=48\)
15*48….n=15
41, 42,….48,…..54, 55
5) We have \(3^2*5\) in 720, so
\(\frac{720}{3^2*5}=16\)
16*45….n=45
If average is 16, we will require 22 integers lesser than 16, and it will result in negative integers too.
Thus, total 5
sting8
Current Student
Joined: 03 Dec 2020
Last visit: 12 Aug 2023
Posts: 55
Given Kudos: 215
Location: India
Debrief: https://gmatclub.com/forum/740-v40-q50-second-attempt-self-preparation-375379.html
Concentration: Technology, Strategy
Schools: ISB '23 (A) Tepper '24 (WL) Ross '24 (D)
GMAT 1: 720 Q49 V39
GMAT 2: 740 Q50 V40
WE:Engineering (Computer Hardware)
26 Jun 2021, 09:59
Kudos
Bookmarks
I had read,
No. of ways to write a number into sum of 2 or more consecutive positive int = no. of odd factors -1.
(Just found a link for this : https://cat.wordpandit.com/cat-number-system-trick/ )
720 = (3^2) * (2^4) * (5^1)
So, no. of odd factors = (2+1) * (1+1) = 6
So, for this question, required answer = 6-1 =5
Am I missing something ? Is there any caveat to the formula, which I am not aware of ?
Bunuel TestPrepUnlimited avigutman GMATinsight EgmatQuantExpert chetan2u
No. of ways to write a number into sum of 2 or more consecutive positive int = no. of odd factors -1.
(Just found a link for this : https://cat.wordpandit.com/cat-number-system-trick/ )
720 = (3^2) * (2^4) * (5^1)
So, no. of odd factors = (2+1) * (1+1) = 6
So, for this question, required answer = 6-1 =5
Am I missing something ? Is there any caveat to the formula, which I am not aware of ?
Bunuel TestPrepUnlimited avigutman GMATinsight EgmatQuantExpert chetan2u
