Assume that $25\%$ of the student body at your school are seniors and that $40\%$ of the students walk to school. If the events are independent and a student from this school is selected at random, calculate the following probabilities.   

1. $P\left(\text{student is not a senior}\right)$

   Hint (a):

   Look at the percentage of the student body that is a senior.
   If the total sum of the student body must be $100\%$, how much is left for students that are not a senior?

2. $P(\text{student is a senior and does not walk to school})$ 

   Hint (b):

   Make an area model.
   Where on the table is $P(\text{senior and does not walk})$?

   	senior $0.25$	not a senior $0.75$
   walk $0.40$
   does not walk $0.60$

3. $P(\text{student walks to school or does not walk to school})$ 

   Hint (c):

   Where on the table is $P(\text{walk or does not walk})$?

4. Identify the sample space in parts (b) and (c) above as a “union” or a “intersection.”