✔ 最佳答案
(1/3)2nd=red
/
(2/4)1st=red \
/ (2/3)2nd=white
\ (2/3)2nd=red
(2/4)1st=white /
\
(1/3)2nd=white
(i) p(same color)
= p(1st red & 2nd red) + p(1st white & 2nd white)
= p(1st red) x p(2nd red) + p(1st white) x p(2nd white)
= 2/4 x 1/3 + 2/4 x 1/3
= 1/3
(ii) p(diff color)
= p(1st red & 2nd white) + p(1st red & 2nd white)
= p(1st red) x p(2nd white) + p(1st red) x p(2nd white)
= 2/4 x 2/3 + 2/4 x 2/3
= 2/3
2008-11-30 21:41:31 補充:
I am sorry I don't know how to draw well here
if you need to refer to the diagram format
you may read your text book or visit here:
http://www.regentsprep.org/Regents/math/tree/Ltree.htm
2008-11-30 21:42:39 補充:
(2/4)1st=red means
[1st=red] is the event
[2/4] is the probrability of the event