Please answer fast.....

Solution : 

Volume of water is,
V = 20 l => 20/1000
V = 0.02 m³
So, mass of the water 
m = density × volume
m = 10³ × 0.02 
m = 20 kg
Hence, force
F = mg
F = 20 × 9.8
F = 196 N 
(a)
(i) Work done by boy and his father 
​​​​​​W = Fd
W = 196 × 20           (d = 20 m)
W = 3920 J
Work done comparison = 3920:3920 => 1:1 

(ii) Power developed by son,
P = Work done/time 
P = 3920/3 × 60
P = 21.7 W
Power developed by father,
P = W/t
P = 3920/2 × 60
P = 32.6 W
(b)
Both of them do same amount of work i.e. 3920 J