Quick question, and great help if possible: I have an exam tomorrow on a database module which I'm revising for, and one of the past papers had this question:

Consider the following three relations:




with primary keys A, C, and E, respectively.
Assume that R1 has 2000 tuples, R2 has 1500 tuples, and R3 has 800

(a) Estimate the size of R1∞R2∞R3 (∞ is a join symbol). [6 marks]

(b) Estimate the size of R3∞R2∞R1 (∞ is a join symbol). [2 marks]
Some of my peers believe the answer to be 0-2000 for both a and b, however some have come up with different answers, and we're not sure which is correct.

What do think for a and b?