I have to construct a cubic spline interpolating function with values given by this table 
During the construction we should take a note that we look for a spline with equidistant knots. Calculate the value of the spline at point 1.5
Now I have done most of the work and came to conclusion of this graph being the cubic spline on each respective interval. I do not however understand the part with equidistant knots. (I know what equidistant knots are).
Not sure how to tackle this "consideration". Thanks for any hits/check ups on the graph.