To determine which river is the longest, we need to compare the distances provided for the Yangtze River and the Nile River.
The distance you mentioned for the Yangtze River is 3940 miles, and for the Nile River, it is 6608 kilometers.
To make a fair comparison, we need to convert the distances to the same unit. Let's convert 3940 miles to kilometers:
1 mile is approximately equal to 1.60934 kilometers.
3940 miles * 1.60934 kilometers/mile = 6337.9066 kilometers (rounded to four decimal places).
Now, we can compare the distances:
Yangtze River: 6337.9066 kilometers
Nile River: 6608 kilometers
Based on these measurements, the Nile River is longer than the Yangtze River by approximately 270.0934 kilometers (rounded to four decimal places).