A non-viscous fluid of constant density of 1000 kg/m³ flows in a stream line motion along a tube of variable cross-section. 
The area of cross-section at two points P and Q of length 5m  are 40cm² and 20cm² respectively. If velocity of fluid at P is 3 m/s then find velocity of fluid at Q. 
 

• A

  3 m/s

• B

  4 m/s

• C

  5 m/s

• D

  6 m/s