For the answer to the question above, to solve the average increase between hours 2 and 4, first let as solve the the number of student in each hour
x = 2f(x) = 4x -1f(2) = 4(2) - 1f(2) = 7
x = 3f(x) = 4x -1f(3) = 4(3) - 1f(3) = 11
x = 4f(x) = 4x -1f(4) = 4(4) - 1f(4) = 15
increase in hours 2 to 4increase per hour = 15 - 7 / 4 - 2increase per hour = 4 students per hour
