SOLUTION: I don't get how to find the area of a circle an d round to the nearest whole number. Will you please help me i will be having a quiz on it 5-31-07 and it is 5-30-07 so please pleas

Algebra ->  Surface-area -> SOLUTION: I don't get how to find the area of a circle an d round to the nearest whole number. Will you please help me i will be having a quiz on it 5-31-07 and it is 5-30-07 so please pleas      Log On


   



Question 83875This question is from textbook Harcourt Math
: I don't get how to find the area of a circle an d round to the nearest whole number. Will you please help me i will be having a quiz on it 5-31-07 and it is 5-30-07 so please please please help me. This question is from textbook Harcourt Math

Found 2 solutions by stanbon, josmiceli:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
find the area of a circle an d round to the nearest whole number.
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Assume you have a circle with a radius = 2.5 inches
Area of a circle = (pi)r^2
Your Circle:
Area = (pi)(2.5)^2
Area = (pi)(6.25)
Area = 19.6346
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Rounding to the nearest whole number
Area = 20 sq. in.
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Chers,
Stan H.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The area of a circle is pi%2Ar%5E2
If you are tol to round your answer to the nearest whole
number, then say your answer is 4.499. This is closer to 4
than it is to 5, so your answer is 4. Say your answer is
4.501. This is closer to 5 than to 4, so your answer is 5.
You have to know what value to use for pi, too. It wmight make
a difference in your answer.
3.141 is 3-place accuracy
3.1415 is 4-place accuracy
3.14159 is 5-place accuracy
You should be told how many decimal places to use on the quiz.
Suppose the radius of a circle is a really big number.
Suppose r+=+5641896 inches, then
A+=+pi%2A5641%5E2
Here, the fewer decimal places you use for pi, the more accuracy you're
going to lose in your answer. I'll try examples, rounding to the nearest
whole number
A%5B1%5D+=+3.141+%2A31820881
A%5B1%5D+=+99949387
A%5B2%5D+=+3.1415+%2A+31820881
A%5B2%5D+=+99965298
I'm getting better and better accuracy with more accurate values of pi.
This is only true because r is a large number. I need just as many decimal
places for pi as there are digits in r. After that I won't get
better accuracy rounded to the nearest whole number.