The equation for buoyant force is: F (buoyant force) = Vpg. Where V =volume in meters^3, p=density of fluid (Kg/m^3), g=acceleration of gravity (9.81m/s^2, a constant). So volume is equal to 9X6X3=162 cm^3 BUT you must convert cm^3 into m^3. 1cm^3=-1.0 X 10^-5. So 162 cm^3=.000162m^3. Density of water =994 kg/m^3 (really 1000kg/m^3, but we must use what your problem uses (994). g=9.81m/s^2. So F=.000162 X 994 X 9.81=1.58N (Newtons).
Please try this on your own! All this information is on the internet. Mr. Tutor won't be there for your test!