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

It is currently 22 Jul 2014, 06:27

Close

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
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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Probability - Heads

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Senior Manager
Senior Manager
avatar
Joined: 10 Dec 2004
Posts: 274
Followers: 1

Kudos [?]: 9 [0], given: 0

GMAT Tests User
Probability - Heads [#permalink] New post 12 Jan 2005, 10:49
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
Two coins are tossed with probability landing at Head not equal to 0.5. What is the probability of getting two Heads out of two tosses?

(1) The probability of getting head is 3 times that of getting tails.
(2) The probability of getting one Head and one Tail is 2/9
Manager
Manager
avatar
Joined: 06 Sep 2004
Posts: 69
Followers: 1

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

 [#permalink] New post 13 Jan 2005, 16:09
A.

P(head) = 3 P(tail)
Also P(head) + P(tail) = 1

So P(head) and P(tail) and therefore P(both heads) can be calculated.

B is insufficient. All it tells is P(A)*P(B)
Director
Director
User avatar
Joined: 07 Jun 2004
Posts: 618
Location: PA
Followers: 2

Kudos [?]: 133 [0], given: 22

GMAT Tests User
 [#permalink] New post 13 Jan 2005, 16:13
I would have to go with C as the Q is asking for the exact value

so we can get it from

a*b = 2/9

and a = 3b
Manager
Manager
avatar
Joined: 14 Dec 2004
Posts: 119
Followers: 1

Kudos [?]: 1 [0], given: 0

 [#permalink] New post 13 Jan 2005, 17:06
Is this analysis correct?

We know that p(h)+p(t)=1
From condition 1: p(h)=3p(t)

Let x = p(t) where 0<x<1:

Then we have: 3x+x=1; Thus x=.25, and p(h)=3x=.75

Thus 1 is sufficient:

From 2, we can't get anything, so final answer is A
Director
Director
User avatar
Joined: 21 Sep 2004
Posts: 619
Followers: 1

Kudos [?]: 3 [0], given: 0

GMAT Tests User
 [#permalink] New post 13 Jan 2005, 17:06
i would go with A. explanation as above.
Director
Director
User avatar
Joined: 07 Jun 2004
Posts: 618
Location: PA
Followers: 2

Kudos [?]: 133 [0], given: 22

GMAT Tests User
 [#permalink] New post 13 Jan 2005, 17:18
guys the above calculation will work for 1 coin but 2 coins are tossed

What is the OA ?
Senior Manager
Senior Manager
avatar
Joined: 22 Jun 2004
Posts: 394
Location: Bangalore, India
Followers: 1

Kudos [?]: 1 [0], given: 0

GMAT Tests User
Re: Probability - Heads [#permalink] New post 13 Jan 2005, 23:45
I would go with B.

P(Two coins with no heads) = 0.5

P(one head and one tail + all heads) = 1-0.5 = 0.5

(1)Insufficient for the above equation
(2)Sufficient because P(one head and one tail ) = 2/9
P(all heads) = P(one head and one tail + all heads) - P(one head and one tail ) = 1/2 - 2/9 = 5/18

Thus, it is B.

pb_india wrote:
Two coins are tossed with probability landing at Head not equal to 0.5. What is the probability of getting two Heads out of two tosses?

(1) The probability of getting head is 3 times that of getting tails.
(2) The probability of getting one Head and one Tail is 2/9

_________________

Awaiting response,

Thnx & Rgds,
Chandra

Senior Manager
Senior Manager
avatar
Joined: 22 Jun 2004
Posts: 394
Location: Bangalore, India
Followers: 1

Kudos [?]: 1 [0], given: 0

GMAT Tests User
 [#permalink] New post 14 Jan 2005, 23:16
Could you justify the OA? Somehow, I could not!!

I appreciate if you let me know why I am wrong in choosing B. That helps me a lot.


pb_india wrote:
OA is "A"

_________________

Awaiting response,

Thnx & Rgds,
Chandra

  [#permalink] 14 Jan 2005, 23:16
    Similar topics Author Replies Last post
Similar
Topics:
1 Probability - Head & Tails.. DeeptiM 3 31 Jul 2011, 20:43
If a coin has a probability of landing heads up or tails TeHCM 2 26 Dec 2005, 18:06
When you throw a coin, the probability of getting head is gamjatang 1 26 Nov 2005, 06:34
What is the probability of getting at most 1 Head mandy 1 09 Sep 2005, 00:42
The probability that a coin falls heads up is 50%. What is forumsmba 1 04 Dec 2004, 16:58
Display posts from previous: Sort by

Probability - Heads

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.