Keiko wants to put a ribbon border along the edge of her round tablecloth. If the diameter of the tablecloth is 42 inches, about how many inches of ribbon will Keiko need to buy to the nearest whole inch?

Answer 1

To find out how much ribbon Keiko needs, we need to calculate the circumference of the round tablecloth. The formula for the circumference \( C \) of a circle is:

\[ C = \pi \times d \]

where \( d \) is the diameter of the circle. In this case, the diameter of the tablecloth is 42 inches.

Now we can substitute this value into the formula:

\[ C = \pi \times 42 \]

Using an approximate value of \( \pi \) (3.14) for calculations, we get:

\[ C \approx 3.14 \times 42 \]

Calculating this gives:

\[ C \approx 131.88 \text{ inches} \]

To find the amount of ribbon Keiko needs to buy, we round this value to the nearest whole inch:

\[ C \approx 132 \text{ inches} \]

Thus, Keiko needs to buy about 132 inches of ribbon.