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 →

OG Pg. 117 (Orange Book)

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 25
Joined: Tue Jul 08, 2008 10:46 pm
Thanked: 4 times
by clubtwofour » Tue Oct 28, 2008 4:31 pm
OG states the following regarding counting methods, "...each time a coin is flipped, there are two possible outcomes, heads and tails. If an experiment consists of 8 consecutive coin flips, then the experiment has 28 possible outcomes, where each of these outcomes is a list of heads and tails in some order."

How did OG calculate that there are 28 possible outcomes? Can someone show the math behind this?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 46
Joined: Mon Jul 07, 2008 12:10 pmFollowed by: 1 member
Location: Atlanta
Thanked: 5 times

by lachlanc » Wed Oct 29, 2008 9:52 am
It is a permutation calculation - n!/k!(n-k)!

8C2 = 8!/2!6!

= 8*7/2 = 56/2 = 28
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 25
Joined: Tue Jul 08, 2008 10:46 pm
Thanked: 4 times

by clubtwofour » Mon Nov 03, 2008 2:02 pm
That makes sense! Thanks!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pmFollowed by: 11 members
Thanked: 331 times

by cramya » Mon Nov 03, 2008 2:42 pm
If I am not mistaken the multiplication principle states that in counting the possibilits of independent events happenning u mutiply the possibilities of these indepenedent events (i.e what comes up in the 2nd flip is independent of what happenned in the 1st flip)


2*2*2*2*2*2*2*2 = 2 ^ 8

Hope this helps!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 871
Joined: Wed Aug 13, 2008 7:48 am
Thanked: 48 times

by stop@800 » Mon Nov 03, 2008 7:22 pm
I agree with cramya, it should be 2^8.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 1
Joined: Thu Sep 26, 2013 12:54 pm

by curious_swan » Thu Sep 26, 2013 1:02 pm
when you flip the coin 8 times there are 256 (2^8) possible combinations (outcomes) considering the probability into account for eg.

it can be be

1. H, H, H, H, H, H, H, T
2. H, H, H, H, H, H, T, T
3. T, T, T, T, T. T, T, H
---
--
up to 256 combinations.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1