Final answer:
The main span of Bridge A is 36.96% shorter than the main span of Bridge B, calculated by finding the length difference and then expressing it as a percentage of Bridge B's span.
Step-by-step explanation:
To calculate how much shorter the main span of Bridge A is compared to Bridge B, we must first find the difference in their lengths and then determine what percentage this difference is of Bridge B's span. The span of Bridge A is 2900 feet, and the span of Bridge B is 4600 feet.
First, find the length difference:
Length difference = Span of Bridge B - Span of Bridge A
Length difference = 4600 feet - 2900 feet
Length difference = 1700 feet.
Next, calculate this as a percentage of Bridge B's span:
Percentage = (Length difference / Span of Bridge B) * 100
Percentage = (1700 feet / 4600 feet) * 100
Percentage = 36.96%.
Therefore, the main span of Bridge A is 36.96% shorter than the main span of Bridge B