X+y=155. Y= -x+155
1.50x +4(-x+155)= 520
1.50x-4x+620=520
-2.5x =-100
X= 40. Y=110
9514 1404 393
Answer:
4 pounds
Step-by-step explanation:
Let b represent the pounds of bananas Mrs. Davis bought. The weight of strawberries would be (7-b) and their cost would be 4×0.50 = 2.00 per pound. Her total purchase was ...
0.50b + 2.00(7 -b) = 8.00
-1.50b +14 = 8 . . . . simplify
6 = 1.50b . . . . . . add 1.50b -8
4 = b . . . . . . . . divide by 1.50
Mrs. Davis bought 4 pounds of bananas.
0.06 is 10 times as much as 0.6

Refer to the attachment for calculations.
(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