BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

flash lights

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Master | Next Rank: 500 Posts
Posts: 447
Joined: Sun Apr 22, 2012 7:13 amFollowed by: 13 members
Thanked: 46 times
GMAT Score:700
by hemant_rajput » Wed Jan 30, 2013 11:23 am
Q17 . At a bookstore, "MODERN BOOK STORE" is flashed using neon lights. The words are individually flashed at long intervals of 5/2, 17/4 and 41/8 sec resp. , and each word is put off after a second. The least time after which the full name of the bookstore can be read again is?
a. 49.5
b. 73.5
c. 1744.5
d. 855
I'm no expert, just trying to work on my skills. If I've made any mistakes please bear with me.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Junior | Next Rank: 30 Posts
Posts: 23
Joined: Wed Feb 23, 2011 7:32 amFollowed by: 2 members
Thanked: 8 times
GMAT Score:740

by vkb001 » Wed Jan 30, 2013 5:56 pm
Initially, every word is flashed for a second. From then, the interval for which each word is put off differs. So, the time length till the next flash for each of the words is 1+5/2, 1+17/4, 1+41/8 = 3.5, 5.25, 6.125.

We need an integer number of each of these durations so that the cumulative duration of each of these words is equal. To put it simply,

m(3.5) = n(5.25) = k(6.125) where m,n,k are all integers.

We need to find the least common multiple of the three numbers.

LCM(3.5,5.25,6.125) = 73.5.

Another way to figure this out in the exam is to check with each number.

Step 1: Try 49.5 (with the lowest)

49.5/3.5 is not an integer. So, reject this option.

Step 2: Try 73.5

73.5/3.5 = 21 (integer!)
73.5/5.25 = 14 (integer!)
73.5/6.125 = 12 (integer!)

BINGO! Answer's (b)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1