a. To complete the table, we have to assign the corresponding study hours per week to the hours worked per week.
For example, for the first interval 0≤h<4, the credits taken are 18 (according to the first table). When the credits taken are 18, the study hours per week are 39 (according to the second table). It means that for the interval 0≤h<4, the study hours per week is 39.
The values of this table will be, respectively:
39, 32, 24, 21, 17, 14, 12.
d. An student works between 12 and 16 hours every week, that allows him take 15 credits, which means that he has to use 21 hours to study. He wants to study 32 hours per week, that way, he can take 17 credits. To achieve it he needs to reduce its working hours to 4 to 8 hours per week, that way he would be able to take 17 credits and study 32 hours per week.
