Question

Building a 200 foot-long bridge across Scorpion Gulch, where the water is 8 feet deep, costs $700,000. Assume that the cost varies directly with the length of the bridge and directly with the square of the depth of the water.

Answer 1

Explanation:

BE SURE TO READ THROUGH.

Represent cost with C, length of bridge with L and depth of water with D.

• & represents directly varies as

; C & L

; C & D²

therefore C & LD²

; C = kLD².......k is a constant

700,000 = k × 200 × 8²

700,000 = k × 200 × 64

700,000 = 12800k

700,000 / 12800 = k

54.6875 = k

The relationship therefore is C = 54.6875 × LD²

What are we then to do??