Answer: 2561.7 pounds
Explanation:
If we assume the total weight of an airplane (in pounds units) as a <u>linear function</u> of the amount of fuel in its tank (in gallons) and we make a Weight vs amount of fuel graph, which resulting slope is 5.7, we can use the slope equation of the line:
(1)
Where:
is the slope of the line
is the airplane weight with 51 gallons of fuel in its tank (assuming we chose the Y axis for the airplane weight in the graph)
is the fuel in airplane's tank for a total weigth of 2390.7 pounds (assuming we chose the X axis for the a,ount of fuel in the tank in the graph)
This means we already have one point of the graph, which coordinate is:

Rewritting (1):
(2)
As Y is a function of X:
(3)
Substituting the known values:
(4)
(5)
(6)
Now, evaluating this function when X=81 (talking about the 81 gallons of fuel in the tank):
(7)
(8) This means the weight of the plane when it has 81 gallons of fuel in its tank is 2561.7 pounds.
Answer:
P = 0.27R from the center
Explanation:
Given,
The radius of the uniform circular plate, R = 2R
The radius of the hole, r = R
The center of the smaller circle from the center is, d = 0.8R
The center of mass of a circular disc with a hole in it given by the formula
P = dr²/R² - r²
Where P is the distance from the center of mass located in the line joining the two centers opposite to the hole.
Substituting the given values in the above equation,
P = 0.8R x R² / 4R² - R²
= 0.27R³/R²
= 0.27R
Hence the center of mass of plate is at a distant P = 0.27R from the center