• 7 CATs FREE!
    If you earn 100 Forum Points

    Engage in the Beat The GMAT forums to earn
    100 points for $49 worth of Veritas practice GMATs FREE

    Veritas Prep
    VERITAS PRACTICE GMAT EXAMS
    Earn 10 Points Per Post
    Earn 10 Points Per Thanks
    Earn 10 Points Per Upvote
    REDEEM NOW

[x] is the greatest integer less than or equal x, what is th

This topic has 3 expert replies and 0 member replies

GMAT/MBA Expert

[x] is the greatest integer less than or equal x, what is th

Post

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

Difficult



[Math Revolution GMAT math practice question]

[x] is the greatest integer less than or equal x, what is the value of [√30]+[√40]+[√50]?

A. 12
B. 15
C. 16
D. 18
E. 20

_________________

Math Revolution
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
Email to : info@mathrevolution.com

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Post
Max@Math Revolution wrote:
[Math Revolution GMAT math practice question]

[x] is the greatest integer less than or equal x, what is the value of [√30]+[√40]+[√50]?

A. 12
B. 15
C. 16
D. 18
E. 20
GIVEN: [x] is the greatest integer less than or equal x
For example, [3.2] = 3, since 3 is the greatest integer that is less than (or equal) to 3.2
Likewise, [8.7] = 8, since 8 is the greatest integer that is less than (or equal to) 8.7

Now onto the question....
√25 = 5
√36 = 6
√49= 7
√64 = 8

Since √30 is BETWEEN √25 (aka 5) and √36 (aka 6), we know that √30 = 5.something
So, [√30] = 5

Since √40 is BETWEEN √36 (aka 6) and √49 (aka 6), we know that √40 = 6.something
So, [√40] = 6

Since √50 is BETWEEN √49 (aka 7) and √64 (aka 8), we know that √50 = 7.something
So, [√50] = 7

So, [√30]+[√40]+[√50] = 5 + 6 + 7 = 18

Answer: D

Cheers,
Brent

_________________
Brent Hanneson – Creator of GMATPrepNow.com
Use our video course along with Beat The GMAT's free 60-Day Study Guide

Sign up for our free Question of the Day emails
And check out all of our free resources

  • +1 Upvote Post
  • Quote
  • Flag
GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months!
Post
Max@Math Revolution wrote:
[Math Revolution GMAT math practice question]

[x] is the greatest integer less than or equal x, what is the value of [√30]+[√40]+[√50]?

A. 12
B. 15
C. 16
D. 18
E. 20
√30 is about 5.4, so [√30] = 5.

√40 is about 6.3, so [√40] = 6.

√50 is about 7.1, so [√50] = 7.

Thus, [√30]+[√40]+[√50] = 5 + 6 + 7 = 18.

Alternate Solution:

The greatest integer whose square is less than 30 is 5 (because 5^2 = 25, but 6^2 = 36 > 30). Therefore, [√30] = 5.

Similarly, the greatest integer whose square is less than 40 is 6 and greatest integer whose square is less than 50 is 7; therefore [√40] = 6 and [√50] = 7.

Thus, [√30]+[√40]+[√50] = 5 + 6 + 7 = 18.

Answer: D

_________________
Scott Woodbury-Stewart Founder and CEO

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Legendary Member
Joined
24 Jul 2015
Posted:
1762 messages
Followed by:
28 members
Upvotes:
19
GMAT Score:
Most Active Expert
Post
=>

Since 5 = √25 < √30 < √36 = 6, we have [√30] = 5.
Since 6 = √36 < √40 < √49 = 7, we have [√40] = 6
Since 7 = √49 < √50 < √64 = 8, we have [√50] = 7
Thus [√30]+[√40]+[√50] = 18.

Therefore, D is the answer.
Answer: D

_________________

Math Revolution
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
Email to : info@mathrevolution.com

  • +1 Upvote Post
  • Quote
  • Flag
  • Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • The Princeton Review
    FREE GMAT Exam
    Know how you'd score today for $0

    Available with Beat the GMAT members only code

    MORE DETAILS
    The Princeton Review
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep

Top First Responders*

1 fskilnik@GMATH 90 first replies
2 Brent@GMATPrepNow 48 first replies
3 Jay@ManhattanReview 43 first replies
4 Rich.C@EMPOWERgma... 26 first replies
5 GMATGuruNY 26 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

Most Active Experts

1 image description fskilnik@GMATH

GMATH Teacher

171 posts
2 image description Scott@TargetTestPrep

Target Test Prep

118 posts
3 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

100 posts
4 image description Max@Math Revolution

Math Revolution

83 posts
5 image description Jay@ManhattanReview

Manhattan Review

71 posts
See More Top Beat The GMAT Experts