Simple probability question

[The_Master]

Hi every body. Could any one help me to solve this problem
http://img78.imageshack.us/img78/5946/untitledgw2.jpg [Broken]
REGARDS

 

[cristo]

This looks like a homework problem. Please note that you must show some work before we can help you. Also, it is easier if you post the question in the thread, instead of linking to it, to enable people who want to help you to refer to the question quickly.