Final answer:
To calculate the circumference of a circle with a given diameter, use the formula C = πd, where C is the circumference and d is the diameter. Substituting the given diameter of 5ft, the circumference is 15.7ft.
Step-by-step explanation:
To calculate the circumference of a circle, you can use the formula C = πd, where C represents the circumference and d represents the diameter of the circle.
In this case, the given diameter is 5ft. Substituting this value into the formula, we have C = π × 5ft.
Using the value of π as approximately 3.14, we can calculate the circumference as C = 3.14 × 5ft = 15.7ft.
Therefore, the correct option is a) 15.7ft.