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

It is currently 21 Oct 2019, 15:46

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

What is the sum of all integers from 45 to 155 inclusive?

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

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58396
What is the sum of all integers from 45 to 155 inclusive?  [#permalink]

Show Tags

New post 17 Oct 2018, 02:48
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

72% (01:09) correct 28% (01:17) wrong based on 110 sessions

HideShow timer Statistics

Senior Manager
Senior Manager
User avatar
P
Joined: 15 Feb 2018
Posts: 372
Premium Member
What is the sum of all integers from 45 to 155 inclusive?  [#permalink]

Show Tags

New post 17 Oct 2018, 03:09
1
1
Inclusive so it is 155-45+1=111 numbers
45+155=200, 46+154=200...99+101
There are 55 pairs like this (\(\frac{111}{2}\) = 55 r 1). The remainder of 1 will be the number 100.
55·200+100=11,100
Intern
Intern
avatar
B
Joined: 30 Sep 2018
Posts: 9
Location: Canada
Schools: DeGroote'21
What is the sum of all integers from 45 to 155 inclusive?  [#permalink]

Show Tags

New post 17 Oct 2018, 10:08
2
Im not sure but wouldnt this be how to solve this question;

Find number of terms: (last term-first term)+1, so (155-45)+1= 110
Then find average of terms: (FT+LT)/2 = (155+45)/3=100

Sum of all terms = mean x number of terms = 110 x 100 = 11000
Senior Manager
Senior Manager
User avatar
P
Joined: 15 Feb 2018
Posts: 372
Premium Member
Re: What is the sum of all integers from 45 to 155 inclusive?  [#permalink]

Show Tags

New post 18 Oct 2018, 04:26
zwander
You recognised the extra 1 "+1" but then didn't include it in the rest of the solution.
See the post above yours that explains it.
Intern
Intern
avatar
B
Joined: 30 Sep 2018
Posts: 9
Location: Canada
Schools: DeGroote'21
Re: What is the sum of all integers from 45 to 155 inclusive?  [#permalink]

Show Tags

New post 18 Oct 2018, 08:47
philipssonicare oh wow what a silly mistake! Thanks for catching it :)
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8117
Location: United States (CA)
Re: What is the sum of all integers from 45 to 155 inclusive?  [#permalink]

Show Tags

New post 19 Oct 2018, 15:23
1
Bunuel wrote:
What is the sum of all integers from 45 to 155 inclusive?

A. 10,000
B. 10,100
C. 11,000
D. 11,100
E. 13,200


A quick way to perform this arithmetic is to recall that if we know the average of a set of numbers, we can multiply by the number of numbers (i.e., the quantity) to get the sum. We can use the equation: sum = average x quantity

average of evenly-spaced set = (smallest number + largest number)/2 = (45 + 155)/2 = 200/2 = 100

quantity = 155 - 45 + 1 = 111

Thus, the sum is 100 x 111 = 11,100

Answer: D
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Intern
Intern
avatar
B
Joined: 05 Sep 2018
Posts: 6
Re: What is the sum of all integers from 45 to 155 inclusive?  [#permalink]

Show Tags

New post 19 Oct 2018, 21:10
Significance of the "+1" when finding number of terms?
GMAT Club Bot
Re: What is the sum of all integers from 45 to 155 inclusive?   [#permalink] 19 Oct 2018, 21:10
Display posts from previous: Sort by

What is the sum of all integers from 45 to 155 inclusive?

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





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