I am new to probability and using One of the books to learn the concepts. I got stuck in following problem.
Any guidance will be highly appreciated.
The mathematics department has 8 graduate assistants who are assigned to the same office. Each assistant is just as likely to study at home as in the office. How many desks must there be in the office so that each assistant has a desk at least 90% of the time?
Probability of each student being in office is 1/2. So probability of all 8 in office is 1/256, similarly 7 in office is 8/256 etc. But I am not able to link these information with the question of how many desks.
Any guidance will be highly appreciated.