I am honestly very lost in the topic of cost of funds.

As I am not sure whats the actual purpose and meaning marginal cost of funds despite having studied the textbook and lecture notes multiple times already..I also don't understand why is the costs of independent source of fund under the marginal cost of funds?

And suddenly, In the notes there is marginal cost of a single source of funds and also pooled cost of funds. (which is supposedly be different from the previous marginal cost of funds...)

Furthermore, they also included weighted marginal cost of funds and weighted average projected cost of funds.

But whats the difference between all these...?

And how do I know which to apply when it comes to exam..

Is there any good notes or books that sir/madam could kindly recommend me for this topic?