• EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT

Rate Filling Tank = Radius

This topic has 1 expert reply and 1 member reply
bml1105 Master | Next Rank: 500 Posts
Joined
24 Nov 2013
Posted:
113 messages
Followed by:
5 members
Thanked:
1 times

Rate Filling Tank = Radius

Post Mon May 19, 2014 9:38 am
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    When a cylindrical tank is filled with water at a rate of 22 cubic meters per hour, the level of water in the tank rises at a rate of 0.7 meters per hour. Which of the following best approximates the radius of the tank in meters?


    (A) (√10)/2
    (B) √10
    (C) 4
    (D) 5
    (E) 10


    Correct Answer: B

    Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
    Post Mon May 19, 2014 9:50 am
    bml1105 wrote:
    When a cylindrical tank is filled with water at a rate of 22 cubic meters per hour, the level of water in the tank rises at a rate of 0.7 meters per hour. Which of the following best approximates the radius of the tank in meters?

    (A) (√10)/2
    (B) √10
    (C) 4
    (D) 5
    (E) 10
    Let's examine what occurs in a 1-hour period
    The volume of water increases by 22 cubic meters.
    The height of the water increases by 0.7 meters.

    So, we need to find the radius of a 0.7 meter high cylinder that has a volume of 22 cubic meters.

    Volume = (pi)r²h
    22 = (pi)r²(0.7)

    IMPORTANT: notice that (pi)(0.7) = approximately 2.2

    So, we get: 22 = (2.2)r²
    Divide both sides by 2.2: 10 = r²
    Solve: r = √10 (approximately)

    Answer: D

    Cheers,
    Brent

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

    Check out the online reviews of our course
    Come see all of our free resources

    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 Mon May 19, 2014 10:37 am
    Hi bml1105,

    This question can also be solved by TESTing THE ANSWERS.

    Volume of a cylinder is…

    V = (pi)(R^2)H

    With a given height of .7 meters, we can TEST the answers to find the one that gives us a Volume of 22.

    While I would normally start with B or D, I'm going to start with C (since it's the smallest of the "nice" answers and it's right in the "middle" of the options)

    If R = 4, we'd have….

    (pi)(4^2)(.7) = 16pi(.7) = approximately 35

    This result is TOO BIG (it's supposed to be 22). This means we can eliminate C and anything bigger than C (D and E).

    Let's test B next. If R = √10…..

    (pi)(10)(.7) = 7pi = approximately 22. This is a MATCH for what we were told.

    Final Answer: B

    GMAT assassins aren't born, they're made,
    Rich

    _________________
    Contact Rich at Rich.C@empowergmat.com

    Best Conversation Starters

    1 lheiannie07 116 topics
    2 ardz24 64 topics
    3 swerve 63 topics
    4 LUANDATO 62 topics
    5 M7MBA 57 topics
    See More Top Beat The GMAT Members...

    Most Active Experts

    1 image description Brent@GMATPrepNow

    GMAT Prep Now Teacher

    170 posts
    2 image description EconomistGMATTutor

    The Economist GMAT Tutor

    129 posts
    3 image description Rich.C@EMPOWERgma...

    EMPOWERgmat

    122 posts
    4 image description GMATGuruNY

    The Princeton Review Teacher

    121 posts
    5 image description Scott@TargetTestPrep

    Target Test Prep

    118 posts
    See More Top Beat The GMAT Experts