Final answer:
The interstate highway system has increased from 16,000 km to 77,000 km since 1960, which constitutes a 381.25% increase in length.
Step-by-step explanation:
The question asks about the percent increase in the distance of interstate highways from 1960 to the present day. The original length was 16,000 km, and it increased to 77,000 km. To calculate the percent increase, you subtract the original length from the new length to find the increase in kilometers, then divide that number by the original length, and finally multiply by 100 to get the percentage.
Calculating the difference: 77,000 km - 16,000 km = 61,000 km
Dividing the increase by the original length gives us the fraction of the increase: 61,000 km / 16,000 km = 3.8125
To convert this to a percentage, we multiply by 100: 3.8125 * 100 = 381.25%
Therefore, the interstate highway system has experienced a 381.25% increase in length since 1960.