Which is the cost per square inch of a pizza with diameter 20 inches if the cost of the pizza is $16? Be sure to round your answer to the nearest cent.

about 1 cent

about 5 cents

about twenty-five cents

about eighty cents
confused help please

Question

Which is the cost per square inch of a pizza with diameter 20 inches if the cost of the pizza is $16? Be sure to round your answer to the nearest cent. 

 about 1 cent 

 about 5 cents 

 about twenty-five cents 

 about eighty cents 
confused help please

phi · Answer

Do you know how to find the area of a circle ?

anonymous · Answer

pi times radius squared

phi · Answer

ok,  if the diameter is 20, what is the radius ?

anonymous · Answer

10?

phi · Answer

yes,  radius is half of a diameter.

now you need to find the area of a circle with r=10
A= pi*r*r = pi*10*10

pi is about 3.1416  (or use a calculator which uses more digits)

A = 3.1416 *100
can you find the area ?

anonymous · Answer

314

mathstudent55 · Answer

Correct.
Now can you write $16 in cents?

phi · Answer

314.16  (you should keep more of the digits)

anonymous · Answer

0.16

phi · Answer

now you need cost per square inch

that means   cost divided by area

can you do that ?

mathstudent55 · Answer

No.
There are 100 cents in $1, so in $16 dollars there are 16 * 100 cents.

anonymous · Answer

19.625

phi · Answer

can you show your work ?

phi · Answer

what is cost divided by area ?  

the cost is $16.  the area is 314.16 square inches

can you divide cost by area to get  dollars per square inch ?

anonymous · Answer

19.635

phi · Answer

How.  Can you show your work ?

phi · Answer

I think you are doing  area divided by cost, which is "upside down"

phi · Answer

cost per square inch  means   cost /  area

NOT area/cost