Fluid Mechanics Venturi meter/manometer

[patep023]

Homework Statement

Question: http://i.imgur.com/aoXUDP1.png

Homework Equations

Q=v1A1=v2A2
Bernoullis Equation
P=P0 + ρgh

The Attempt at a Solution

I have got an answer of 3.55*10^-3 m^3 /s. The answer i have been told is 1.29 x 10-3 m3s-1. I am not sure if i am wrong or the answer given to me is wrong. would highly appreciate it if someone could work out the answer and check if I am wrong or not.
Here is my attempt of the question but it is all over the place. http://i.imgur.com/d4anv1Q.jpg

 

[paisiello2]

It's difficult to follow your hand writing but can you explain explicitly what you are doing in line 2 of your calcs?

 

[patep023]

I think the answer given to me was incorrect for that one, i did a similar question and got the right answer for it ;D
I was writing down another equation in respect to the manometer so i can cancel stuff around