Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Two dimensional sample space

  1. May 6, 2010 #1
    Let’s select two numbers x and y such that 1<=x<=4 and 2<=y<=6. What is the probability of x +y>=5?
    I solved the problem and attached it. Please check my solution and tell me whether my approach of solution is correct or wrong. The most puzzling matter is that I'm getting two different answers. Any suggestion would be of great help to me regarding my attempted solution. Thanks.

    Attached Files:

    • 1.jpg
      File size:
      22.1 KB
    • 2.jpg
      File size:
      16.3 KB
  2. jcsd
  3. May 6, 2010 #2


    User Avatar
    Science Advisor

    The thumbnails are almost unreadable.
  4. May 10, 2010 #3
    If I'm reading what you are doing correctly, it looks like the sample space you drew is an "or" rather than an "and". That is your first picture looks like 1<x<4 "or" 2<y<6. If you do an "and" instead then you should get a box, not a tetris piece.
  5. May 11, 2010 #4
    I think if you graph all three equations, you will see a geometric way
    of getting the answer, and use integration to do it.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook