Costs Analysis based on the structure file

Question

I'm preparing for my RDBMS theorical exams, and I'm stuck in a concept.

A hashed index has an occupancy of the 80% of a page, which means that the data file size will be 1.25.

Why 1.25? Because 0.25 corresponds to 1/4, which is the 20% of the missing 80%.

What if the occupancy will be 90% or 70%? What will be then the data-file size?

I tried with a simple relation based on what I already know:

80% : 1.25 = 70% : X ---> X = (1.25 * 0.7)/1.25 = 1.09375.

I do not know if the computation that I performed above is correct.

Any Help?

Answer 1

If you pay 100 (dollars or whatever) for some item, but can get a 20% discount, you pay only 20. But going back to 100 requires adding 25% to the 80.

Some scammers take advantage of 'customers' by using this mathematical slight of hand.

80% = 4/5

125% = 5/4

Note the pattern.