So we're looking at two rectangles, one cut out of the other, so all you do is find the area of the big one, base times height equals area, minus the area of the small one, base times height equals area. So the equation you have to solve for is this,
Area=(12.6X14)-(3X8.4)
17.5 because 140 divided by 35 is 17.5 and so is 70 divided by 35.
The volume of a cone is
V = (1/3)πr³
We are given with radius and the height of cone, so we can solve for the radius as function of water level using ratio and proportion
3/9 = r/h
r = h/3
Substituting
V = πh³/81
Taking the derivative
dV/dt = πh²/27 dh/dt
Solving for dh/dt given
dV/dt = 10 m³/s
and
h = 3 m
dh/dt = 9.55 m/s
60% is 0.60 so you do 0.60 x 29 which = to 17.4
so your answer is 17.40 or 17.4 is 60% of 29
