4. Consider a join of relation r and relation s. Suppose that schema for r is (Name, YearOfBirth, Profession) and schema for relation s is (Year, Month, Week, HoroscopeText). Given that n_r = 1000 and V(YearOfBirth, r) = 42 and n_s = 500 and V(Year, s) = 10

a. What are the two different estimates for the size of join result of r _{YearOfBirth=Year} s?

b. Which one is more accurate?