Given
The demand function

To determine:
a) The revenue function.
b) The marginal revenue.
c) The marginal revenue when x=200.
d) The equation of tangent, and its derivation.
Explanation:
It is given that,

a) The revenue function is given by,

b) The marginal revenue function is,

c) The marginal revenue when x=200 is,

Hence, the marginal revenue is 3.84.
d) Let y=mx+c is the tangent.
Then,

That implies, for y=12.68, and x=200,

Hence, the equation of tangent is,
I think this is the answer
Answer:
V = 192 m^3
Step-by-step explanation:
The volume of a cuboid is given by
V = l*w*h
V = 4m * 6m *8m
V = 192 m^3
Answer:
The velocity is 8.93 meters/second.
Step-by-step explanation:
It is given that Elena runs for 28 seconds and finishes at 250 meters.
Here the displacement is 250 meters and the time is 28 seconds.
We know that 
Substitute displacement = 250 and time = 28 in above formula.

meters/second
Hence, the velocity is 8.93 meters/second.