Find the water volume of the pool. The formula for a vertical cylinder is V = pi*r^2*h, which here is V = pi(13 ft)^2*(4 ft) = 676*pi cubic feet.
Now convert this 676 cu. ft. to gallons:
Mult (676*pi cu ft) by the conversion factor (7.48 gal) / (1 cu ft):
676*pi cu ft 7.48 gal
--------------- * ------------- = 5056*pi gallons (rounded down from 5056.48 pi)
1 1 cu ft
The cost of filling the pool will be
5056.48*pi gallons $3
--------------------------- * ------------- = $48 (to the nearest dollar)
1 1000 gal
Step-by-step explanation:
Will bought several books that cost $ 2.50 each and received a $ 2 discount on the total bill. If he paid $ 10.50, how many books did he buy ?
2.50x - 2.00 = 10.50
2.50x = 10.50 + 2.00
2.50x = 12.50
x = 12.50/2.50
x = 5....he bought 5 books
If you borrowed $100, then your monthly payment is $2.44
If you borrowed $200, then your monthly payment is 2*2.44 = 4.88
etc etc
We can set up a proportion
2.44/100 = x/13300
to figure out the monthly payment x. Cross multiply and solve for x
2.44*13300 = 100*x
100x = 2.44*13300
100x = 32452
x = 32452/100
x = 324.52
So the monthly payment is $324.52
An alternative way to get this monthly payment is to apply 2.44% to 13300, which is another way to view the phrase "monthly payment per $100 is 2.44"
------------------
There are 48 months in 4 years (start with 12 mon = 1 yr, then multiply both sides by 4) so we multiply 48 by the monthly payment to get the result 48*324.52 = 15,576.96. This is the total amount you have to pay back which is the principal plus interest.
Subtract off the principal (amount borrowed) to find the interest or finance charge: 15,576.96 - 13,300 = 2,276.96
Answer: Choice B
You do the implcit differentation, then solve for y' and check where this is defined.
In your case: Differentiate implicitly: 2xy + x²y' - y² - x*2yy' = 0
Solve for y': y'(x²-2xy) +2xy - y² = 0
y' = (2xy-y²) / (x²-2xy)
Check where defined: y' is not defined if the denominator becomes zero, i.e.
x² - 2xy = 0 x(x - 2y) = 0
This has formal solutions x=0 and y=x/2. Now we check whether these values are possible for the initially given definition of y:
0^2*y - 0*y^2 =? 4 0 =? 4
This is impossible, hence the function is not defined for 0, and we can disregard this.
x^2*(x/2) - x(x/2)^2 =? 4 x^3/2 - x^3/4 = 4 x^3/4 = 4 x^3=16 x^3 = 16 x = cubicroot(16)
This is a possible value for y, so we have a point where y is defined, but not y'.
The solution to all of it is hence D - { cubicroot(16) }, where D is the domain of y (which nobody has asked for in this example :-).
(Actually, the check whether 0 is in D is superfluous: If you write as solution D - { 0, cubicroot(16) }, this is also correct - only it so happens that 0 is not in D, so the set difference cannot take it out of there ...).
If someone asks for that D, you have to solve the definition for y and find that domain - I don't know of any [general] way to find the domain without solving for the explicit function).
