Question

HELP PLEASE. A pizza shop charges customers based on the area of the pizza they order. The cost of a pizza in dollars can be represented

by so) - 0.1 ser? where r is the radius of the pizza in inches.
What is the diameter of a pizza that costs $26.32? Round to the nearest hundredth.
o 9.15 inches
O 18.30 inches
O 83.72 inches
o 217.63 inches

Answer 1

The correct answer is B. 18.30 inches

Explanation:

1. Let's review the information provided to us to answer the question correctly:

Cost of the pizza = $ 0.10 * π * r², where r = radius of the pizza in inches

2. What is the diameter of a pizza that costs $26.32 ?

Let's recall the formula of the area of a circle, in this case, the area of the pizza:

Area = π * r², therefore the constant 0.10 that is multiplying the area of the pizza, is the cost of the pizza in dollars per square inch.

Cost of the pizza = $ 0.10 * π * r²

Replacing with the values we have:

26.32 = 0.10 * 3.1416 * r²

26.32 = 0.31416 * r²

r² = 26.32/0.31416

r² = 83.78

r = √ 83.78

r = 9.15 inches ⇒ d = 9.15 * 2 = 18.30

The correct answer is B. 18.30 inches

Answer 2

For this case we have that the cost of each pizza is given by the following function:

`S (r) = 0.1 \pi * r ^ 2`

Where:

r: It's the radius of the pizza

IF a pizza cost $26.32 we have:

`26.32 = 0.1 \pi * r ^ 2`

We cleared the radius, using
`\pi = 3.14`:

`\frac {26.32} {0.1} = \pi * r ^ 2\\263.2 = 3.14r ^ 2\\\frac {263.2} {3.14} = r ^ 2\\83.82 = r ^ 2\\r = \pm \sqrt {83.82}`

We choose the positive value:

`r = 9.15`

So, the radius of the pizza is
`9.16 \ in`

Then, the diameter is:
`2r = 2 * 9.15 = 18.30 \ in`

Finally, the diameter of the pizza is:
`18.30 \ in`

Answer:

Option B