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

 It is currently 05 Dec 2013, 04:38

# Events & Promotions

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

# Three cards are drawn from an ordinary 52-card deck without

Author Message
TAGS:
SVP
Joined: 30 Sep 2004
Posts: 1500
Location: Germany
Followers: 4

Kudos [?]: 19 [0], given: 0

Three cards are drawn from an ordinary 52-card deck without [#permalink]  12 Jan 2005, 05:05
1. Three cards are drawn from an ordinary 52-card deck without
replacement (drawn cards are not placed back in the deck). The probability that none of the three cards is a heart is as follows

(a)39/52
(b)38/51
(c)37/50
(d)703/1700
(e)267/1700

my problem below=>

ok it is a simple problem, but my question concerns the two ways of finding the solution.

1. Prob (first card is not heart ) * Prob (second card is not heart GIVEN THAT first is not heart) * Prob (Third card is not heart GIVEN THAT first two are not hearts) = required Prob

38/52*38/51*37/50=703/1700

2. Prob (first card is heart ) * Prob (second card is heart GIVEN THAT first is heart) * Prob (Third card is heart GIVEN THAT first two are hearts) = Prob => 1-Prob = required Prob

13/52*12/51*11/50=1716/132600=1-1716/132600=1678/1700

can someon explain to me why i get two different solutions ???
Senior Manager
Joined: 22 Jun 2004
Posts: 396
Location: Bangalore, India
Followers: 1

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

Re: probability 64 [#permalink]  12 Jan 2005, 05:47
It is 39/52 * 38/51 * 37/50 = Ans d:

None of the cards has to be heart. => all the three can be hearts or any one can be heart or any two can be hearts. You need to add up all these before you subtract from 1. That is where the second answer you have given is different.

christoph wrote:
1. Three cards are drawn from an ordinary 52-card deck without
replacement (drawn cards are not placed back in the deck). The probability that none of the three cards is a heart is as follows

(a)39/52
(b)38/51
(c)37/50
(d)703/1700
(e)267/1700

my problem below=>

ok it is a simple problem, but my question concerns the two ways of finding the solution.

1. Prob (first card is not heart ) * Prob (second card is not heart GIVEN THAT first is not heart) * Prob (Third card is not heart GIVEN THAT first two are not hearts) = required Prob

38/52*38/51*37/50=703/1700

2. Prob (first card is heart ) * Prob (second card is heart GIVEN THAT first is heart) * Prob (Third card is heart GIVEN THAT first two are hearts) = Prob => 1-Prob = required Prob

13/52*12/51*11/50=1716/132600=1-1716/132600=1678/1700

can someon explain to me why i get two different solutions ???

_________________

Awaiting response,

Thnx & Rgds,
Chandra

SVP
Joined: 30 Sep 2004
Posts: 1500
Location: Germany
Followers: 4

Kudos [?]: 19 [0], given: 0

right...i misread "none" ! thanx !
Manager
Joined: 31 Aug 2004
Posts: 170
Followers: 1

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

I still get a different answer:

13/52+12/51+11/50=1199/1700
1-1199/1700=501/1700

Why?
SVP
Joined: 30 Sep 2004
Posts: 1500
Location: Germany
Followers: 4

Kudos [?]: 19 [0], given: 0

this is a better way to find the solution, cause in your attempt you forgot the possibilty that there are two or one hearts. it is also an AND-problem, so you have to multiply. first draw AND second draw AND third draw.

Prob (first card is not heart ) * Prob (second card is not heart GIVEN THAT first is not heart) * Prob (Third card is not heart GIVEN THAT first two are not hearts) = required Prob

38/52*38/51*37/50=703/1700
Similar topics Replies Last post
Similar
Topics:
A card is drawn from an ordinary deck of 52 well-shuffled 9 10 Dec 2003, 05:35
Two cards are drawn at random from a pack of 52 cards. Find 6 22 Nov 2005, 06:26
In a deck of cards there are 52 cards numbered from 1 to 13. 2 28 Jan 2006, 08:01
You have a deck of 52 cards; if you draw 3 cards without 6 31 Aug 2007, 04:08
2 Four cards are randomly drawn from a pack of 52 cards. Find 14 01 Jun 2010, 23:36
Display posts from previous: Sort by