probability question

• crucifiedx

  17 Aug 10, 21:51

  1. and

  2. or

  which one must multiply and which one must add?

• FireIce

  17 Aug 10, 22:22

  and is X
  
  or is +

• -StarDust-

  17 Aug 10, 22:23

  Originally posted by crucifiedx:

  1. and

  2. or

  which one must multiply and which one must add?

  
  I dont get wad u meant.

• crucifiedx

  17 Aug 10, 22:24

  thanks. :)

• Xpoloppx

  20 Sep 10, 16:37

  for  example,

                            r

             3/4      /

                   r

      3/4    /

         P

      1/4    \

                   nr

                1/4    \

                              nr

   

  ...both days will rain. r x r

                                   =3/4 x 3/4

                                   =9/16 (and)

  ...either one day will rain. (r x nr) + (r x nr)

                                           =(3/4 x 1/4) + (3/4 x 1/4)

                                           =3/8(or)

  u understand?