Question

The tree house will be 8 feet off the ground. Peter will hang a rope, with knots tied for foot holds. Each knot uses an additional 2 inches of rope. Write an expression for the length of the rope needed if Peter ties n knots and wants the rope to touch the ground. How many inches of rope are needed if there are 8 knots? Explain.

Answer 1

The tree house is 8 feet off the ground, or 96 inches up because (8)(12) = 96. Each knot needs 2 extra inches, so the expression for the length of rope needed is 96 + 2n. If n = 8, then Peter will need 96 + 2(8) = 112 inches of rope.

Answer 2

L(k)=8(12)+2k

L(k)=96+2k

L(8)=96+2(8)

L(8)=96+16

L(8)=112in