It is equal to 2× 2 = 4 circles around the tree, and the remaining 1× 2 = 2 meters.
When the volume is 30% off, it is 1.5m around the tree.
It is equal to circling the tree 1× 3 = 3 times, and the rest: 1.5× 3 = 4.5 meters.
The circumference of the trunk is equal to:
( 1.5×3- 1×2)÷(2×2- 1×3)
=(4.5-2)÷(4-3)
=2.5÷ 1
= 2.5 meters
Length of rope:
2.5×2×2+ 1×2
= 10+2
= 12 (m)