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

 It is currently 12 Dec 2013, 01:13

# Events & Promotions

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

# Set problem

Author Message
TAGS:
Intern
Joined: 26 Feb 2011
Posts: 45
Followers: 1

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

Set problem [#permalink]  01 Mar 2011, 08:32
00:00

Difficulty:

5% (low)

Question Stats:

75% (00:00) correct 25% (00:00) wrong based on 4 sessions
If x is to be chosen at random from the set {1,2,3,4} and y is to be chosen at random from the set {5,6,7}, what`s the probability that xy will be even?
A/ 1/6
B/ 1/3
C/ 1/2
D/ 2/3
E/ 5/6
[Reveal] Spoiler: OA
Math Expert
Joined: 02 Sep 2009
Posts: 15129
Followers: 2534

Kudos [?]: 15619 [0], given: 1564

Re: Set problem [#permalink]  01 Mar 2011, 08:42
Expert's post
If x is to be chosen at random from the set {1,2,3,4} and y is to be chosen at random from the set {5,6,7}, what`s the probability that xy will be even?
A/ 1/6
B/ 1/3
C/ 1/2
D/ 2/3
E/ 5/6

The product to be even either one or both must be even, so:
P(x=even OR y=even)=P(x=even)+P(y=even)-P(x=even AND y=even)=2/4+1/3-2/4*1/3=2/3;

Or: P(xy=even)=1-P(xy=odd)=1-2/4*2/3=2/3, so basically we find the probability of the product to be odd (which happens when both x and y are odd) and subtract it from 1.

_________________
Re: Set problem   [#permalink] 01 Mar 2011, 08:42
Similar topics Replies Last post
Similar
Topics:
Help requred for Sets problem 8 08 Apr 2005, 02:24
Problem Sets for sale... 0 18 Aug 2005, 14:15
Sets problem 4 07 Sep 2009, 16:04
Sets Problem 5 11 Jan 2010, 09:38
A marketing firm determined that, of 200 households 7 28 Apr 2008, 17:14
Display posts from previous: Sort by