Correct answer is... 9525 kg. It is equal to 21000 lbs. Empty weight of Northrop YF-17 is total weight of the airframe, engine, avionics and all other systems installed by manufacturer. It is higher weight then empty speed of other aircrafts of a similar size. Average is about 1402 kg (3091 lbs).
The biggest civil aircraft has empty weight of 250,000 kg (628,000 lb), so Northrop YF-17 has 4% percent of it's weight. Typical jet airliner has about 39,500 kg (87,100 lb), so in the comparision Northrop YF-17 has 24% of aircrafts like B737 or A320.
Disclaimer: Our articles and data connected to empty weight of Northrop YF-17 are based on public data from various sources. We are very picky to select an reliable data providers, but we cannot guarantee that everything is 100% error-proof. We recommend for any serious purpose - as a rule of thumb - to request offical data about empty weight from manufacturer of Northrop YF-17.