<span>In order to answer her question regarding how many students at her high school had summer jobs Nan must follow the procedure given in answer option B: First, randomly select 100 students, then ask them if they have summer jobs. In statistics this method is known as Population Sampling. These 100 students are chosen at random in order to avoid bias - we need them to be representative of the entire high school population.</span>
Answer:
Give up.
Explanation:
Physics is horrible.
And that's the cold hard truth. :(
To solve the problem, it is necessary to apply the concepts related to the change of mass flow for both entry and exit.
The general formula is defined by

Where,
mass flow rate
Density
V = Velocity
Our values are divided by inlet(1) and outlet(2) by





PART A) Applying the flow equation we have to



PART B) For the exit area we need to arrange the equation in function of Area, that is



Therefore the Area at the end is 
C) The longer the line, the greater the magnitude of the vector. As for the direction, just think of a compass.
Here's a formula that's simple and useful, and if you're really in
high school physics, I'd be surprised if you haven't see it before.
This one is so simple and useful that I'd suggest memorizing it,
so it's always in your toolbox.
This formula tells how far an object travels in how much time,
when it's accelerating:
Distance = (1/2 acceleration) x (Time²).
D = 1/2 A T²
For your student who dropped an object out of the window,
Distance = 19.6 m
Acceleration = gravity = 9.8 m/s²
D = 1/2 G T²
19.6 = 4.9 T²
Divide each side by 4.9 : 4 = T²
Square root each side: 2 = T
When an object is dropped in Earth gravity,
it takes 2 seconds to fall the first 19.6 meters.