The weight of a body in air is 100N. How much will it weight in water, if it displaced 400 cc of water?

$U=V{\rho }_{w}g$

$\Rightarrow$  $U=\left(400\times {10}^{-6}\right)\left(1000\right)\left(9.8\right)$

$\Rightarrow$  $U=3.92N$

 $W\text{'}=W-U$

$\Rightarrow$  $W\text{'}=100-3.92$

$\Rightarrow$  $W\text{'}=96.08N$