The following picture shows a circular driveway with a flowerbed that lies in the middle. A family ?

Question

The following picture shows a circular driveway with a flowerbed that lies in the middle. A family is planning to asphalt the driveway and knows the diameter of the whole circle is 20 feet and the radius of the circular flowerbed is 3 feet.

a.What is the area of the flowerbed? Show all work and round to the nearest hundredths place.

b. What is the area of the whole circle (the driveway and the flowerbed)? Show all work and round to the nearest hundredths place.

c If the driveway costs $5.00 per square foot to asphalt, what will be the total cost to asphalt the driveway? Show all work and round to the nearest dollar

Answer 1

The area of a circle is pi times the square of the radius.  That is ALL you need to solve every part of this problem.

Answer 2

area = pi multiplied by r ²

a) The flowerbed has a radius of 3

area = pi * 9 (I'll leave you to calculate it)

b) The whole circle has a radius of 10 (half of the diameter, 20).

area = pi * r ² (go ahead and calculate that)

c) The driveway area is the whole circle area minus the flowerbed area.  Multiply that by 5 to get the cost to asphalt the driveway.

Answer 3

a. to get the area of a circle, you should use the formula

A=3.14(r)(r)

where r = radius

Solution:

A= 3.14(3)(3)

  = 3.14(9)

  = 28.26

s0 the area of the flowerbed is 28.26 square feet

b. to get the area of the whole circle, you will use the following formulas

:we have to get the radius first

d= 2r

20= 2r

2r = 20

2r/2=20/2

r = 10

: solving for the area

A= 3.14 (10)(10)

  = 3.14 (100)

  = 314

So the area of the whole circle is 314 square feet.

c. to get radius of the driveway, subtract the area of the flowerbed to the area of the whole circle

A= 314 - 28.26

   = 285.74 square feet = area of driveway

to get the total cost

$= 5A

  = 5(285.74)

  = 1428.7

  =$1429 is the total cost