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 Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Re: Hard probability ! [#permalink]
21 Aug 2010, 12:54

All possible events = (1/2)^5= 1/32 all the favorable events HHHHH HHHTT THHHT TTHHH HHHHT THHHH that makes 6 favourable events Hence answer will 6/32 = 1/4 therefore B
_________________

I will give a Fight till the End

"To dream anything that you want to dream, that is the beauty of the human mind. To do anything that you want to do, that is the strength of the human will. To trust yourself, to test your limits, that is the courage to succeed." - Bernard Edmonds

A person who is afraid of Failure can never succeed -- Amneet Padda

Re: Hard probability ! [#permalink]
23 Aug 2011, 16:51

Bunuel - U rock. +1 for you.

Cheers.!
_________________

----------------------------------------------------------------------------------------- What you do TODAY is important because you're exchanging a day of your life for it! -----------------------------------------------------------------------------------------

A fair coin is tossed 5 times. What is the probability of getting at least three heads on consecutive tosses?

A. 3/16 B. 1/4 C. 7/24 D. 5/16 E. 15/32

Kaplan says the answer is 1/4. I think the answer is 3/16 because I have interpreted the qn as: What is the probability of getting atleast 3 consecutive heads -> 3 consecutive heads or 4 consecutive heads or 5 consecutive heads ?

Re: PS: Probability [#permalink]
24 Mar 2012, 13:29

Expert's post

shahlanuk wrote:

A fair coin is tossed 5 times. What is the probability of getting at least three heads on consecutive tosses?

A. 3/16 B. 1/4 C. 7/24 D. 5/16 E. 15/32

Kaplan says the answer is 1/4. I think the answer is 3/16 because I have interpreted the qn as: What is the probability of getting atleast 3 consecutive heads -> 3 consecutive heads or 4 consecutive heads or 5 consecutive heads ?

Merging similar topics.

Your interpretation is correct: at least 3 consecutive heads means 3, 4, or 5 consecutive heads, but the answer is still 1/4. Please check the solution provided above and ask if anything remains unclear.
_________________

Re: A fair coin is tossed 5 times. What is the probability of [#permalink]
15 Jul 2013, 06:03

1

This post received KUDOS

In this type of problems where repetition of values is allowed, the total number of possibilities is given by the formula n^r where n is 2 and has the values Heads and Tails. r is 5 and is equal to the number of tosses.

1. Total number of possibilities = 2^5 = 32 2. Instances of favorable outcomes:

(i) HHH** - Let us elaborate all the possibilities:

1. HHH HH 2. HHH HT 3. HHH TH 4. HHH TT

We have exhausted the possibilities.

(ii) We also have the following **HHH and the possibilities are:

5. HH HHH 6.HT HHH 7,TH HHH 8.TT HHH

(iii) and the following: *HHH*

9. H HHH H 10, H HHH T 11. T HHH H 12. T HHH T

Out of the total 12 , only 8 are unique.

3. The probability is 8/32 = 1/4. _________________