Venturi Tube Question: Help Solve & Find the Right Answer

[traceurrr]

Hey guys. I can't figure out part 3bii) of this Venturi Tube Question.

The answer I keep getting is 3.7907E-03 but it should be 3.95E-03. I'm definitely missing something but can't figure out what. I'm out by about 5%, could it just be down to rounding errors?

Question and my working is shown in the attached pictures.

Question:

Attempted Answer:

Would really appreciate any help. Thanks!

 

[SteamKing]

What units are you using? Your calculations are not complete unless you indicate your units.