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

 It is currently 23 Jul 2018, 01:12

### 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

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

# The formula for the sum of squares of integer between 1 and n is n(

Author Message
TAGS:

### Hide Tags

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 5876
GMAT 1: 760 Q51 V42
GPA: 3.82
The formula for the sum of squares of integer between 1 and n is n(  [#permalink]

### Show Tags

25 Sep 2017, 00:52
00:00

Difficulty:

25% (medium)

Question Stats:

77% (01:28) correct 23% (01:29) wrong based on 47 sessions

### HideShow timer Statistics

[GMAT math practice question]

The formula for the sum of squares of integer between 1 and n is n(n+1)(2n+1) / 6 = 1^2 + 2^2 + … + n^2. The is the value of 11^2 + 12^2 + … + 20^2?

A. 2470
B. 2475
C. 2480
D. 2485
E. 2490

_________________

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 $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" PS Forum Moderator Joined: 25 Feb 2013 Posts: 1185 Location: India GPA: 3.82 The formula for the sum of squares of integer between 1 and n is n( [#permalink] ### Show Tags 25 Sep 2017, 09:50 2 MathRevolution wrote: [GMAT math practice question] The formula for the sum of squares of integer between 1 and n is n(n+1)(2n+1) / 6 = 1^2 + 2^2 + … + n^2. The is the value of 11^2 + 12^2 + … + 20^2? A. 2470 B. 2475 C. 2480 D. 2485 E. 2490 Sum of squares from 1 to 20 $$= \frac{20*21*41}{6} = 2870$$ (use the formula given) Sum of squares from 1 to 10 $$= \frac{10*11*21}{6} = 385$$ Hence sum of squares from 11 to 20 $$=$$ Sum of squares from 1 to 20 $$-$$ sum of squares from 1 to 10 $$= 2870-385 = 2485$$ Option D Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 5876 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: The formula for the sum of squares of integer between 1 and n is n( [#permalink] ### Show Tags 27 Sep 2017, 01:39 => 11^2 + 12^2 + … + 20^2 = ( 1^2 + 2^2 + … + 20^2 ) – (1^2 + 2^2 + … + 10^2) = 20∙21∙41/6 - 10∙11∙21/6 = 2870 – 385 = 2485 Ans: D _________________ 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$99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Re: The formula for the sum of squares of integer between 1 and n is n( &nbs [#permalink] 27 Sep 2017, 01:39
Display posts from previous: Sort by

# Events & Promotions

 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®.