A source follower is required to connect a high-resistance source to a load

A source follower is required to connect a high-resistance source to a load whose resistance is nominally 2kOhm but can be as low as 1.5kOhm and as high as 5kOhm. What is the maxiumum output resistance that the source follower must have if the output voltage is to remain within +/-10 percent of nominal value? If the MOSFET has Kn=2.5 mA/V^2 , at what current ID must it be biased? At what overdrive voltage is the MOSFET operation?