Question 20

The circumference of a circle with a radius of 5 inches is 31.4 inches.

To find the circumference of a circle, the formula used is C = 2πr. Substituting the radius of 5 inches and using π ~ 3.14, we calculate C = 2 * 3.14 * 5, which equals 31.4 inches.

A) 15.7 inches

This option is incorrect. If we mistakenly calculate the circumference as C = πr, using a radius of 5 inches and π ~ 3.14, we would arrive at 15.7 inches, which does not apply to the circumference formula that requires the factor of 2.

B) 78.5 inches

This option is also incorrect. The value 78.5 inches could result from an incorrect application of the circumference formula, possibly by using a radius that is too large or miscalculating the multiplication of π and the radius.

C) 10 inches

Option C is incorrect. This value does not accurately reflect the circumference calculation using the proper formula. It may represent a misunderstanding of the relationship between radius and circumference, as the value is far too small for a radius of 5 inches.

D) 31.4 inches

This is the correct answer. By applying the formula C = 2πr with a radius of 5 inches and π ~ 3.14, we correctly calculate the circumference as 31.4 inches.

Conclusion

The correct answer, 31.4 inches, is derived from the proper application of the circumference formula, confirming that all other options either miscalculate or misinterpret the relationship between the radius and circumference. This highlights the importance of using the correct formula when determining the circumference of a circle.