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

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • 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
  • 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
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep

The present ratio of students to teachers (OG2016)

This topic has 1 expert reply and 0 member replies
boomgoesthegmat Senior | Next Rank: 100 Posts Default Avatar
Joined
25 Apr 2016
Posted:
93 messages
Thanked:
1 times

The present ratio of students to teachers (OG2016)

Post Fri May 06, 2016 12:38 pm
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    The present ratio of students to teachers at a certain school is 30 to 1. If the student enrollment were to increase by 50 students and the number of teachers were to increase by 5, the ratio of students to teachers would then be 25 to 1. What is the present number of teachers?

    A) 5
    B) 8
    C) 10
    D) 12
    E) 15

    OA: E

    Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
    Post Fri May 06, 2016 3:12 pm
    boomgoesthegmat wrote:
    The present ratio of students to teachers at a certain school is 30 to 1. If the student enrollment were to increase by 50 students and the number of teachers were to increase by 5, the ratio of students to teachers would then be 25 to 1. What is the present number of teachers?

    A) 5
    B) 8
    C) 10
    D) 12
    E) 15
    I like to use two variables for these "changing ratios" questions.

    The PRESENT ratio of students to teachers at a certain school is 30 to 1
    Let S = # of students PRESENTLY
    Let T = # of teachers PRESENTLY
    We can write: S/T = 30/1
    Cross multiply to get: (1)(S) = (30)(T)
    Simplify: S = 30T

    If the student enrollment were to increase by 50 students and the number of teachers were to increase by 5, the ratio of students to teachers would then be 25 to 1
    In this scenario...
    S + 50 = # of students
    T + 5 = # of teachers
    So, we get: (S + 50)/(T + 5) = 25/1
    Cross multiply to get: (S + 50)(1) = (25)(T + 5)
    Expand: S + 50 = 25T + 125
    Simplify to get: S = 25T + 75

    We now have 2 equations with 2 variables:
    S = 30T
    S = 25T + 75

    To solve, replace S in the bottom equation with 30T
    We get: 30T = 25T + 75
    So: 5T = 75
    Solve: T = 15
    So, there are PRESENTLY 15 teachers

    Answer: E

    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

    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!

    Best Conversation Starters

    1 Vincen 180 topics
    2 lheiannie07 61 topics
    3 Roland2rule 61 topics
    4 ardz24 40 topics
    5 VJesus12 14 topics
    See More Top Beat The GMAT Members...

    Most Active Experts

    1 image description Brent@GMATPrepNow

    GMAT Prep Now Teacher

    160 posts
    2 image description Rich.C@EMPOWERgma...

    EMPOWERgmat

    102 posts
    3 image description GMATGuruNY

    The Princeton Review Teacher

    99 posts
    4 image description Jay@ManhattanReview

    Manhattan Review

    86 posts
    5 image description Matt@VeritasPrep

    Veritas Prep

    80 posts
    See More Top Beat The GMAT Experts