math help for 10 year old which this parent dunno?

Question

a) the circumference of a circle is greater than two times the width. how would u have predicted this?
b) the base of amy's finger is 15 mm wide. predict the circumference of a ring that would fit her finger. explain your prediction.

thanks.

Answer 1

a) The width is also known as the diameter.
The circumference equals pi times diameter.
pi is approximately 3.14, and since 3.14 is greater than 2, you know that the circumference is more than twice the diameter (width).

b) C = 15(pi) = 47.1239 mm

Answer 2

A)Circumference and Area of Circles
The perimeter of a circle is called the circumference. All circles are similar. Therefore, for any two circles, the ratio of the perimeters (circumferences) is the same as the ratio of the diameters. The ratio of the circumference to the diameter in each circle is the same. This constant ratio of circumference to diameter is denoted by the Greek letter π (pi).
B)Measuring the finger-Perimeter and Area
The perimeter of a polygon is the distance around it, or the sum of the lengths of its sides. For a simple figure like a rectangle, opposite sides are congruent. Let l and w denote the length and width of a rectangle. The perimeter, P, is given by P = 2l + 2w.

Area is measured in square units. A square unit is a square in which each side has a length of one unit. The area of an object is the number of square units it takes to cover the object without any overlap. The area, A, of a rectangle is given by the formula l × w (length times width) or b × h (base times height). This can be understood from the following rectangle of base 3 and height 2. There are two rows of three squares each, so there are 3 × 2 = 6 square units.

Answer 3

I think these answers are missing the point. The assignment is likely asking how can you guess at the answer without knowning geometric formulae including the pi ratio. So you might use reasoning by physical analogy. See how difficult it is to get your hand around a certain object which is circular in cross section e.g. a coffee mug. Then see how if you put 2 such mugs side by side touching that your hand could span the distance from the outside of the one to the far outside of the other. Thus you would predict the relationship in "a".

Answer 4

MATH, ACTIVITIES and FUN.

http://www.sosmath.com/wwwsites.html

http://www.webmath.com/index.html

http://mathforum.org/dr.math/

http://www.tc.cornell.edu/Services/Education/Gateways/Math_and_Science/mathematics.htm

Kindergarten to 8th Grade Interactive Sites

http://www.theproblemsite.com/math_games.asp

http://www.internet4classrooms.com/skills_4th.htm

http://www.apples4theteacher.com/math.html

http://www.kidsolr.com/math/index.html

http://www.center.k12.mo.us/edtech/edm/4.htm

Good luck.

Kevin, Liverpool, England.

Answer 5

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