3. a. In a class of 45 students, 25 study physics, 30 study Biology and 10 study both physics
and Biology. A student is selected at random from the class. Find the probability that he
or she is studying:
A
i. Only physics
ii. one subjects
b. A woman had 642 oranges in a basket. After selling of them she found that of the
remaining were bad. How many of the remaining were good?
c. Given that vector AB = and BC=
Find AC