Answer:
a). total length of rope=132 m
b). total cost of the rope=$528
Step-by-step explanation:
Step 1
To get the total length of rope needed to cover the circular garden twice, we express this as;
P=πD
where;
P=perimeter
π=pi
D=diameter
In our case;
π=22/7
D=21 m
replacing;
P=(22/7)×21=66 m
2×P=2×66=132 m
total length of rope=132 m
Step 2
The expression to calculate the total cost can be written as;
total cost=cost per meter length×total length of rope
where;
cost per meter=$4
total length of rope=132 m
replacing;
total cost=4×132=$528
total cost of the rope=$528
