Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 27 Apr 2015, 01:03

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Need help with probabilities

Author Message
Intern
Joined: 06 Sep 2013
Posts: 1
Followers: 0

Kudos [?]: 0 [0], given: 0

Need help with probabilities [#permalink]  09 Oct 2013, 22:31
Will be gratefull for help in solving 2 questions:
1. When a coin is tossed for 6 times, what is the probability that after the first tossing, every outcome will be different from previous one?
2. If n is an integer from 1 to 96, what is the probability for n*(n+1)*(n+2) being divisible by 8?
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 5433
Location: Pune, India
Followers: 1324

Kudos [?]: 6715 [0], given: 176

Re: Need help with probabilities [#permalink]  11 Oct 2013, 02:08
Expert's post
DDM wrote:
Will be gratefull for help in solving 2 questions:
1. When a coin is tossed for 6 times, what is the probability that after the first tossing, every outcome will be different from previous one?

The first toss can be anything H or T. Probability = 1
The second toss must be the opposite. Say if first was H, the second must be T. Probability = 1/2
The third must be opposite again i.e. H now. Probability = 1/2
The fourth must be T. Probability = 1/2
Fifth must be H. Probability = 1/2
Sixth must be T. Probability = 1/2

So overall probability = $1*(1/2)*(1/2)*(1/2)*(1/2)*(1/2) = 1/2^5$

Or think of it this way.
The favorable outcomes are only two: HTHTHT or THTHTH
The total outcomes = $2^6$
Probability $= 2/2^6 = 1/2^5$
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Veritas Prep GMAT course is coming to India. Enroll in our weeklong Immersion Course that starts March 29!

Veritas Prep Reviews

Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 5433
Location: Pune, India
Followers: 1324

Kudos [?]: 6715 [0], given: 176

Re: Need help with probabilities [#permalink]  11 Oct 2013, 02:21
Expert's post
DDM wrote:
2. If n is an integer from 1 to 96, what is the probability for n*(n+1)*(n+2) being divisible by 8?

This one has been discussed here: if-an-integer-n-is-to-be-chosen-at-random-from-the-integers-126654.html
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Veritas Prep GMAT course is coming to India. Enroll in our weeklong Immersion Course that starts March 29!

Veritas Prep Reviews

Re: Need help with probabilities   [#permalink] 11 Oct 2013, 02:21
Similar topics Replies Last post
Similar
Topics:
2 Need help in probability and combinatorics 3 04 Jun 2014, 21:52
3 Probability questions need help. 4 03 Jul 2010, 11:54
probability math(combinations (nCk)) help needed 5 18 Jan 2010, 15:39
probability basics... need help 2 03 Jun 2006, 08:46
Display posts from previous: Sort by