Live GMAT classes with Target Test Prep start Nov 21 and Nov 22. First class free.

See classes
Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

Newsweek Readers’ Choice Awards 2026 winner: Target Test Prep, #1 Test Prep

Target Test Prep was voted #1 Best Test Prep in the 2026 Newsweek Readers’ Choice™ Awards.

★★★★★5.0563 reviews
GMATLiveTeachStarts Nov 22
Josh Braslow, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Josh Braslow, 20+ years in test prep

Nov 22 · Josh Braslow
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemandStart anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

EXECUTIVE ASSESSMENT

with

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget Test Prep
GMATOnDemandStart anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions

Number properties + probability

Expert replies
by ellexay » Wed Feb 11, 2009 7:23 am
) If one number is chosen at random from the first 1000 positive integers, what is the probability that the number chosen is multiple of both 2 and 8?



Soln: Any multiple of 8 is also a multiple of 2 so we need to find the multiples of 8 from 0 to 1000
the first one is 8 and the last one is 1000
==> ((1000-8)/8) + 1 = 125
==> p (picking a multiple of 2 & 8) = 125/1000 = 1/8

Where did they get this 1000-8/8 +1 formula from? Can someone verify this answer? Thank you.
Join the discussion
Source: — Problem Solving |

by DanaJ » Wed Feb 11, 2009 7:57 am
I personally have no idea where they took that formula from. I know what i would do: divide 1000 by 8 and, after noticing that 1000 is a multiple of 8, then it is clear that the number of multiples of 8 is 1000/8 = 125. If you had smth that was not a multiple of 8 (say 1003), I'd divide this number by 8 as well and use the quotient for my answer.
Join the discussion

Re: Number properties + probability

by x2suresh » Wed Feb 11, 2009 9:25 am
ellexay wrote:) If one number is chosen at random from the first 1000 positive integers, what is the probability that the number chosen is multiple of both 2 and 8?



Soln: Any multiple of 8 is also a multiple of 2 so we need to find the multiples of 8 from 0 to 1000
the first one is 8 and the last one is 1000
==> ((1000-8)/8) + 1 = 125
==> p (picking a multiple of 2 & 8) = 125/1000 = 1/8

Where did they get this 1000-8/8 +1 formula from? Can someone verify this answer? Thank you.

first multiple of 8 between 1 and 1000 =8
last multiple of 8 between 1 and 1000 = 1000

total number of multiples = (1000-8)/8 = 124
Above forumula excluding number 8 itself..
So final answer = 124+1=125
Join the discussion

Re: Number properties + probability

by piyush_nitt » Thu Feb 12, 2009 4:36 am
ellexay wrote:) If one number is chosen at random from the first 1000 positive integers, what is the probability that the number chosen is multiple of both 2 and 8?



Soln: Any multiple of 8 is also a multiple of 2 so we need to find the multiples of 8 from 0 to 1000
the first one is 8 and the last one is 1000
==> ((1000-8)/8) + 1 = 125
==> p (picking a multiple of 2 & 8) = 125/1000 = 1/8

Where did they get this 1000-8/8 +1 formula from? Can someone verify this answer? Thank you.
AP formula

to determine the nth term

An = A+ (n-1)d

where An - nth Term
A - first term
n - number of terms
d - difference

In this case

1000 = 8 + (n-1)8

(1000-8) = (n-1)8

(1000-8)/8 + 1 = n
Join the discussion