Results 1 to 2 of 2

Math Help - 52 card deck (a red or a 7)

  1. #1
    Newbie
    Joined
    Jun 2008
    Posts
    6

    52 card deck (a red or a 7)

    Hi, here is my question. From a 52 card deck, what is the probability that I will pull a red or a 7. I got 1/26. Is this right.?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by Hunt67 View Post
    Hi, here is my question. From a 52 card deck, what is the probability that I will pull a red or a 7. I got 1/26. Is this right.?
    how did you get that?

    method 1: count how many choices you have:

    there are 26 red cards, including 2 7s, besides that, there are two 7s, so that we have 28 choices in all out of 52. thus the probability is 28/52 = 7/13



    method 2: use the formula

    for two events A and B

    P(A \cup B) = P(A) + P(B) - P(A \cap B)

    here that translates to P( \text{red or 7}) = P(\text{red}) + P(7) - P( \text{red and 7}) = \frac {26}{52} + \frac 4{52} - \frac 2{52} = \frac 7{13}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Card Deck Question
    Posted in the Statistics Forum
    Replies: 5
    Last Post: September 11th 2010, 01:13 PM
  2. probability of 52 card deck
    Posted in the Statistics Forum
    Replies: 2
    Last Post: January 21st 2010, 07:39 AM
  3. From a 52 card deck, how many 4 card hands ...
    Posted in the Advanced Statistics Forum
    Replies: 5
    Last Post: September 25th 2008, 09:48 AM
  4. Probability 1 card from deck 4 or 6??
    Posted in the Statistics Forum
    Replies: 2
    Last Post: June 22nd 2008, 05:47 PM
  5. Standard 52 card deck
    Posted in the Statistics Forum
    Replies: 3
    Last Post: October 14th 2007, 06:50 PM

Search Tags


/mathhelpforum @mathhelpforum