Let x = total distance he covered
3x/4 by bus
1/2 . x/4 = x/8 by jogging
the remaining distance = x/8 by walking
thus x/8 = 800ft
x = 8 . 800 = 6400ft
9514 1404 393
Answer:
3 months
Step-by-step explanation:
We don't know what's on your list of "useful financial formulas." One that can be used here is the formula for simple interest:
I = Prt . . . . . interest on principal P at annual rate r for t years
Solving for t gives ...
t = I/(Pr)
Filling in the given values, we can find t to be ...
t = 138/(4800×0.115) = 138/552 = 1/4
1/4 year is 3 months -- the duration of the loan.
(a) First find the intersections of

and

:

So the area of

is given by

If you're not familiar with the error function

, then you will not be able to find an exact answer. Fortunately, I see this is a question on a calculator based exam, so you can use whatever built-in function you have on your calculator to evaluate the integral. You should get something around 0.5141.
(b) Find the intersections of the line

with

.

So the area of

is given by


which is approximately 1.546.
(c) The easiest method for finding the volume of the solid of revolution is via the disk method. Each cross-section of the solid is a circle with radius perpendicular to the x-axis, determined by the vertical distance from the curve

and the line

, or

. The area of any such circle is

times the square of its radius. Since the curve intersects the axis of revolution at

and

, the volume would be given by