Answer
a) See diagram
b) 40 pages of economics
Work Step by Step
a) First, determine the maximum number of pages of sociology and economics Maria can read in a day (in 5 hours, Maria can either read a maximum of 100 pages of economics or 250 pages of sociology). These will be the endpoints of Maria's PPF. Then, work through the combinations of hours of reading economics and sociology Maria can do (for example, Maria can choose to do 1 hour of economics and 4 hours of sociology, or 3 hours of economics and 2 hours of sociology). Plot the rest of these points on the graph to obtain Maria's PPF.
b) 100 pages of sociology = 2 hours = 40 pages of economics